Based on the conclusions of domestic and foreign research, we have analyzed the collapse-fall characteristics of overlying strata and the mechanism of aquifer-protective mining in shallow coal seam working faces at th...Based on the conclusions of domestic and foreign research, we have analyzed the collapse-fall characteristics of overlying strata and the mechanism of aquifer-protective mining in shallow coal seam working faces at the Shendong Mine. We have selected the height of the water-conducting fracture zone in overlying strata as a composite index and established the applicable conditions of aquifer-protective mining in shallow coal seams with a multi-factor synthetic-index classification method. From our calculations and analyses of variance, we used factors such as the overlying strata strength, mining disturbing factors and rock integrity as related factors of the composite index. We have classified the applicable conditions of aquifer-protective mining in shallow coal seams into seven types by comparing the result of the height of water-conducting fractured zones of long-wall and short-wall working faces with the thickness of the bedrock, the thickness of the weathered zone and the size of safety coal-rock pillars. As a result, we propose the preliminary classification system of aquifer-protective mining in shallow coal seams. It can provide a theoretical guidance for safe applications of aquifer-protective mining technology in shallow coal seams under similar conditions.展开更多
A set of adaptable conditions classification of aquifer-protective mining in the Iongwall coalface for shallow coal seams with thin bedrock was put forward to deal with the conflict between water protection and high e...A set of adaptable conditions classification of aquifer-protective mining in the Iongwall coalface for shallow coal seams with thin bedrock was put forward to deal with the conflict between water protection and high efficiency for the mining field in west China. This classification was suitable for shallow coal seams with different thickness and was beneficial to the local environmental protection. Using the 3-Universal Distinct Element Code （3DEC） numerical software, the height of the fractured zones for shallow coal seams with thin bedrock was calculated and analyzed, and its predicting formula was achieved. Meanwhile, according to the lithology and the weathering degree of the shallow coal seam the thickness of the protective layer was determined as 10 m and the overlying water body of loose water-bearing sand for shallow coal seams with thin bedrock was divided into three types, namely, weak, medium and strong. Based on these, the necessary bedrock thickness of the Iongwall coalface for shallow coal seams with thin bedrock was confined according to the different mining height and water yield nature of the overlying loose water-bearing sand. Combined with the present mining status, a set of new methods of adaptable conditions classification of aquifer-protective mining technology in the Iongwall coalface for shallow coal seams with thin bedrock was put forward.展开更多
La Cantera Oriente is a shallow freshwater volcanic water body located at an altitude of 2 270 m above sea level in the Ecological Reserve of San Angel Pedregal of Mexico City （Mexico）. In order to ensure the conser...La Cantera Oriente is a shallow freshwater volcanic water body located at an altitude of 2 270 m above sea level in the Ecological Reserve of San Angel Pedregal of Mexico City （Mexico）. In order to ensure the conservation of its biological heritage including zooplankton, the present work was undertaken to quantify the seasonal changes in the diversity and density of rotifers and the selected physico- chemical variables during 2013-2014. Qualitative analysis of the zooplankton samples yielded 68 rotifer species which represented 24 genera in 15 families. Brachionus calyciflorus Pallas, 1766, B. quadridentatus Hermann, 1783, Polyarthra vulgaris Carlin, 1943, Lecane closterocerca （Schmarda, 1859） and Keratella cochlearis （Gosse, 1851） were the most common species. Preston plots of species frequency-density revealed that as many as 30% of the rotifer taxa were dominant throughout the year. The species with high population densities were Brachionus quadridentatus, Lecane closterocerca, Keratella cochlearis, and Lepadellapatella; their peak densities were 2 000, 1 000, 180 and 90 ind./L, all occurring in summer. Canonical correspondence analysis showed that Platyias quadricornis was related to the concentration of phosphates available in the environment and the conductivity, while B. quadridentatus was positively correlated with chlorophyll-a. The trophic status of the lake was eutrophic based on Chl-a content but oligotrophic with relation to the Braehionus： Trichocerca ratio.展开更多
To constrain short-term changes of climate and oceanography in the northern South China Sea （SCS） over interglacial marine isotope stage （MIS） 5.5, we studied planktic and benthic δ18O records of seven marine sed...To constrain short-term changes of climate and oceanography in the northern South China Sea （SCS） over interglacial marine isotope stage （MIS） 5.5, we studied planktic and benthic δ18O records of seven marine sediment cores with a time resolution of 70-700 yr. Using 6-8 tie points the planktic records were tuned to the U/Th chronology of speleothem δ180 records in China and Europe. The last occurrence of pink Globigerinoides ruber marks the top of Heinrich stadial 11 （HS-11） near 128.4 ka. HS-11 matches a 2300-yr long positive δ180 excursion by 1.5/0.8‰ both in planktic and benthic δ18O records. Hence half of the planktic δ180 signal was linked to increased upwelling of δ18O- and 12C-enriched deep waters in the southwestern SCS. The increase was possibly linked to a strengthened inflow of Pacific deep waters through the Bashi Strait, that form a boundary current along the northern slope of the SCS, building a major sediment drift. At its lower margin near 2300-2400 m water depth （w.d.） Parasound records reveal a belt of modern erosion. At the end of glacial termination 2, stratigraphic gaps deleted HS-11 in core MD05-2904 and subsequent peak MIS 5.5 at ODP Site 1144. Likewise hiatuses probably earmarked all preced- ing glacial terminations at Site 1144 back to 650 ka. Accordingly, boundary current erosion then shifted -300 m upslope to ~2040-2060 m w.d. These vertical shifts imply a rise in boundary current buoyancy, that in turn may be linked to transient events of North Pacific deepwater formation similar to that traced in SCS and North Pacific paleoceanographic records over glacial termination 1.展开更多
During anther development, the tapetum pro- vides materials and nutrients for pollen development. In Arabidopsis, several transcription factors have been iden- tified to form a genetic pathway （DYT1-TDF1-AMS- MS188-...During anther development, the tapetum pro- vides materials and nutrients for pollen development. In Arabidopsis, several transcription factors have been iden- tified to form a genetic pathway （DYT1-TDF1-AMS- MS188-MS1） for tapetal development and function. DEFECTIVE in TAPETAL DEVELOPMENT and FUNCTION1 （TDF1） is a member of the R2R3 MYB family and is essential for early tapetum development in Arabidopsis. Here, we characterized an ortholog of Ara- bidopsis TDF1 in rice, OsTDF1 （LOC_Os03g18480）. OsTDF1 shares 69 % amino acid sequence identity with AtTDF1 in the putative MYB domain near the N-terminal region. RT-PCR and in situ hybridization show that OsTDF1 is specifically expressed in tapetal cells of rice anthers. The expression of OsTDF1 in Arabidopsis tdfl mutant restores its fertility, suggesting that this homolog can fulfill the normal function of TDF1 in Arabidopsis. The ostdfl knockout mutant exhibits a male-sterile phenotype. Its tapetal cells exhibit a vacuolated and hypertrophic phenotype similar to that of Arabidopsis tdfl mutants. Terminal deoxynucleotidyl transferase-mediated dUTP nick end labeling assays revealed OsTDF1 acts as an essential regulator for tapetum programmed cell death. The qRT-PCR analysis revealed that OsTDF1 acts downstream of UDT1 and upstream of TDR, EAT1, OsMYBI03 and PTCI in rice, suggesting that the genetic pathway for tapetum development is generally conserved between rice and Arabidopsis,展开更多
基金Financial support for this work, provided by the research fund of the North China Institute of Science and Technology (No.A09002)the National Natural Science Foundation of China (No.50834005)the National Basic Research Program of China (No.2007CB209402)
文摘Based on the conclusions of domestic and foreign research, we have analyzed the collapse-fall characteristics of overlying strata and the mechanism of aquifer-protective mining in shallow coal seam working faces at the Shendong Mine. We have selected the height of the water-conducting fracture zone in overlying strata as a composite index and established the applicable conditions of aquifer-protective mining in shallow coal seams with a multi-factor synthetic-index classification method. From our calculations and analyses of variance, we used factors such as the overlying strata strength, mining disturbing factors and rock integrity as related factors of the composite index. We have classified the applicable conditions of aquifer-protective mining in shallow coal seams into seven types by comparing the result of the height of water-conducting fractured zones of long-wall and short-wall working faces with the thickness of the bedrock, the thickness of the weathered zone and the size of safety coal-rock pillars. As a result, we propose the preliminary classification system of aquifer-protective mining in shallow coal seams. It can provide a theoretical guidance for safe applications of aquifer-protective mining technology in shallow coal seams under similar conditions.
基金Supported by National Natural Science Foundation of China(50904063)the 2007 Research Fund of the State Key Laboratory of Coal Resources and Mine Safety(07KF09)Scientific Research Foundation of China University of Mining & Technology(2008A003,2005B002)
文摘A set of adaptable conditions classification of aquifer-protective mining in the Iongwall coalface for shallow coal seams with thin bedrock was put forward to deal with the conflict between water protection and high efficiency for the mining field in west China. This classification was suitable for shallow coal seams with different thickness and was beneficial to the local environmental protection. Using the 3-Universal Distinct Element Code （3DEC） numerical software, the height of the fractured zones for shallow coal seams with thin bedrock was calculated and analyzed, and its predicting formula was achieved. Meanwhile, according to the lithology and the weathering degree of the shallow coal seam the thickness of the protective layer was determined as 10 m and the overlying water body of loose water-bearing sand for shallow coal seams with thin bedrock was divided into three types, namely, weak, medium and strong. Based on these, the necessary bedrock thickness of the Iongwall coalface for shallow coal seams with thin bedrock was confined according to the different mining height and water yield nature of the overlying loose water-bearing sand. Combined with the present mining status, a set of new methods of adaptable conditions classification of aquifer-protective mining technology in the Iongwall coalface for shallow coal seams with thin bedrock was put forward.
文摘La Cantera Oriente is a shallow freshwater volcanic water body located at an altitude of 2 270 m above sea level in the Ecological Reserve of San Angel Pedregal of Mexico City （Mexico）. In order to ensure the conservation of its biological heritage including zooplankton, the present work was undertaken to quantify the seasonal changes in the diversity and density of rotifers and the selected physico- chemical variables during 2013-2014. Qualitative analysis of the zooplankton samples yielded 68 rotifer species which represented 24 genera in 15 families. Brachionus calyciflorus Pallas, 1766, B. quadridentatus Hermann, 1783, Polyarthra vulgaris Carlin, 1943, Lecane closterocerca （Schmarda, 1859） and Keratella cochlearis （Gosse, 1851） were the most common species. Preston plots of species frequency-density revealed that as many as 30% of the rotifer taxa were dominant throughout the year. The species with high population densities were Brachionus quadridentatus, Lecane closterocerca, Keratella cochlearis, and Lepadellapatella; their peak densities were 2 000, 1 000, 180 and 90 ind./L, all occurring in summer. Canonical correspondence analysis showed that Platyias quadricornis was related to the concentration of phosphates available in the environment and the conductivity, while B. quadridentatus was positively correlated with chlorophyll-a. The trophic status of the lake was eutrophic based on Chl-a content but oligotrophic with relation to the Braehionus： Trichocerca ratio.
基金the National Natural Science Foundation of China(Grant Nos.91028004 and 41023004)
文摘To constrain short-term changes of climate and oceanography in the northern South China Sea （SCS） over interglacial marine isotope stage （MIS） 5.5, we studied planktic and benthic δ18O records of seven marine sediment cores with a time resolution of 70-700 yr. Using 6-8 tie points the planktic records were tuned to the U/Th chronology of speleothem δ180 records in China and Europe. The last occurrence of pink Globigerinoides ruber marks the top of Heinrich stadial 11 （HS-11） near 128.4 ka. HS-11 matches a 2300-yr long positive δ180 excursion by 1.5/0.8‰ both in planktic and benthic δ18O records. Hence half of the planktic δ180 signal was linked to increased upwelling of δ18O- and 12C-enriched deep waters in the southwestern SCS. The increase was possibly linked to a strengthened inflow of Pacific deep waters through the Bashi Strait, that form a boundary current along the northern slope of the SCS, building a major sediment drift. At its lower margin near 2300-2400 m water depth （w.d.） Parasound records reveal a belt of modern erosion. At the end of glacial termination 2, stratigraphic gaps deleted HS-11 in core MD05-2904 and subsequent peak MIS 5.5 at ODP Site 1144. Likewise hiatuses probably earmarked all preced- ing glacial terminations at Site 1144 back to 650 ka. Accordingly, boundary current erosion then shifted -300 m upslope to ~2040-2060 m w.d. These vertical shifts imply a rise in boundary current buoyancy, that in turn may be linked to transient events of North Pacific deepwater formation similar to that traced in SCS and North Pacific paleoceanographic records over glacial termination 1.
基金This work was supported by the grants from the Ministry of Science and Technology of China （2013CB945100）, the National Natural Science Foundation of China （31100227）.
文摘During anther development, the tapetum pro- vides materials and nutrients for pollen development. In Arabidopsis, several transcription factors have been iden- tified to form a genetic pathway （DYT1-TDF1-AMS- MS188-MS1） for tapetal development and function. DEFECTIVE in TAPETAL DEVELOPMENT and FUNCTION1 （TDF1） is a member of the R2R3 MYB family and is essential for early tapetum development in Arabidopsis. Here, we characterized an ortholog of Ara- bidopsis TDF1 in rice, OsTDF1 （LOC_Os03g18480）. OsTDF1 shares 69 % amino acid sequence identity with AtTDF1 in the putative MYB domain near the N-terminal region. RT-PCR and in situ hybridization show that OsTDF1 is specifically expressed in tapetal cells of rice anthers. The expression of OsTDF1 in Arabidopsis tdfl mutant restores its fertility, suggesting that this homolog can fulfill the normal function of TDF1 in Arabidopsis. The ostdfl knockout mutant exhibits a male-sterile phenotype. Its tapetal cells exhibit a vacuolated and hypertrophic phenotype similar to that of Arabidopsis tdfl mutants. Terminal deoxynucleotidyl transferase-mediated dUTP nick end labeling assays revealed OsTDF1 acts as an essential regulator for tapetum programmed cell death. The qRT-PCR analysis revealed that OsTDF1 acts downstream of UDT1 and upstream of TDR, EAT1, OsMYBI03 and PTCI in rice, suggesting that the genetic pathway for tapetum development is generally conserved between rice and Arabidopsis,
