Differences are found in the attributes of microseismic events caused by coal seam rupture,underground structure activation,and groundwater movement in coal mine production.Based on these differences,accurate classific...Differences are found in the attributes of microseismic events caused by coal seam rupture,underground structure activation,and groundwater movement in coal mine production.Based on these differences,accurate classification and analysis of microseismic events are important for the water inrush warning of the coal mine working facefloor.Cluster analysis,which classifies samples according to data similarity,has remarkable advantages in nonlinear classification.A water inrush early warning method for coal minefloors is proposed in this paper.First,the short time average over long time average(STA/LTA)method is used to identify effective events from continuous microseismic records to realize the identification of microseismic events in coal mines.Then,ten attributes of microseismic events are extracted,and cluster analysis is conducted in the attribute domain to realize unsupervised classification of microseismic events.Clustering results of synthetic andfield data demonstrate the effectiveness of the proposed method.The analysis offield data clustering results shows that thefirst kind of events with time change rules is of considerable importance to the early warning of water inrush from the coal mine working facefloor.展开更多
We investigate the subsurface heat exchange process in EGS （enhanced geothermal systems） with a previously developed novel model. This model treats the porous heat reservoir as an equivalent porous medium of a singl...We investigate the subsurface heat exchange process in EGS （enhanced geothermal systems） with a previously developed novel model. This model treats the porous heat reservoir as an equivalent porous medium of a single porosity. However, it considers local thermal non-equilibrium between solid rock matrix and fluid flowing in the factures and employs two energy conservation equations to describe heat transfer in the rock matrix and in the fractures, respectively, enabling the modeling and analyses of convective heat exchange in the heat reservoir. Another salient feature of this model is its capability of simulating the complete subsurface heat exchange process in EGS. The EGS subsurface geometry of interest physically consists of multiple domains： open channels for injection and production wells, the artificial heat reservoir, and the rocks enclosing the heat reservoir, while computationally we treat it as a single-domain of multiple sub-regions associated with different sets of characteristic properties （porosity and permeability, etc.）. This circumvents typical difficulties about matching boundary conditions between sub-domains in traditional multi-domain approaches and facilitates numerical implementation and simulation of the complete subsurface heat exchange process. This model is used to perform a comprehensive parametric study with respect to an imaginary doublet EGS. Effects of several parameters, including the permeability of heat reservoir, heat exchange coefficient in the heat reservoir, the specific area of fractures in the heat reservoir, and thermal compensation from surrounding rocks, on the heat extraction efficiency and EGS lifetime are analyzed.展开更多
Present study describes the results of an efficient protocol for the isolation of good quality DNA from human saliva. The protocol includes collection of saliva in sterile specimen tubes, followed by the cell lysis. A...Present study describes the results of an efficient protocol for the isolation of good quality DNA from human saliva. The protocol includes collection of saliva in sterile specimen tubes, followed by the cell lysis. After formation of cell lysate, proteins wereextracted by phenol chloroform treatment for purification of DNA. The purified DNA was precipitated by adding equal volume of isopropanol to the treated supernatant. After isolation DNA pellet was washed with 70% ethanol, air-dried and was suspended in 30 pL of double distilled water. Best quality of DNA was extracted from the saliva samples and the PCR product was amplified for hyper-variable regions （HVI＆ HV2） of the mitochondrial DNA. The genes were cleaned with GeneAll gel elution kit （Gel SV） （Cat. No. 102-10） and sequenced accordingly. The DNA isolation protocol presented here is recommended for the isolation, best quality and yield of DNA from the human saliva.展开更多
Sedimentary pigments are useful proxy indicators of phytoplankton biomass, community structure, primary productivity and human influence in lacustrine and oceanic ecosystems. Pigments are relatively labile due to thei...Sedimentary pigments are useful proxy indicators of phytoplankton biomass, community structure, primary productivity and human influence in lacustrine and oceanic ecosystems. Pigments are relatively labile due to their complex chemical structures, which makes the extraction and analysis of sedimentary pigments challenging. In addition, it is important to select appropriate methods to study sedimentary pigments in regions which lack previous investigations. In this study, we adopted the L9（34） orthogonal design to develop methods of extraction and HPLC （high performance liquid chromatography） analysis of sedimentary pigments at two lakes on the Tibetan Plateau： meromictic lake-Dagze Co and dimictic lake-Jiang Co. The orthogonal design comprises 9 combinations of various parameters for extraction and HPLC analysis. The results show that the type and volume of solvent are the most important factors for pigment extraction, and the mobile phase and column selection are the most important for HPLC analysis. For the study sites, we found that the best methods to extract sedimentary pigments are as follows： the use of a mixture of acetone：methanol：water （80： 15：5, v：v：v） as the extraction solvent; sol- vent/sample ratio of 10 mL/g; sonication for 30 s and standing extraction for 6 h. The best methods for HPLC analysis are as follows： Zorbax Eclipse plus C8 column with mobile phase A, methanol：acetonitrile：0.25 M aqueous pyridine （50： 25：25, v ： v ： v） and mobile phase B, methanol： acetonitrile： acetone （20： 60： 20, v： v： v）; pH of mobile phase A adjusted to 6 with acetic acid; and HPLC column temperature maintained at 40~C. The study provides an experimental basis for future investigations of past changes in primary productivity and the response of lake ecosystems to climate change and human activities on the Tibetan Plateau.展开更多
基金supported in part by the National Natural Science Foundation of China under Grant 41904098in part by the Beijing Nova Program under Grant 2022056in part by the National Natural Science Foundation of China (52174218)。
文摘Differences are found in the attributes of microseismic events caused by coal seam rupture,underground structure activation,and groundwater movement in coal mine production.Based on these differences,accurate classification and analysis of microseismic events are important for the water inrush warning of the coal mine working facefloor.Cluster analysis,which classifies samples according to data similarity,has remarkable advantages in nonlinear classification.A water inrush early warning method for coal minefloors is proposed in this paper.First,the short time average over long time average(STA/LTA)method is used to identify effective events from continuous microseismic records to realize the identification of microseismic events in coal mines.Then,ten attributes of microseismic events are extracted,and cluster analysis is conducted in the attribute domain to realize unsupervised classification of microseismic events.Clustering results of synthetic andfield data demonstrate the effectiveness of the proposed method.The analysis offield data clustering results shows that thefirst kind of events with time change rules is of considerable importance to the early warning of water inrush from the coal mine working facefloor.
文摘We investigate the subsurface heat exchange process in EGS （enhanced geothermal systems） with a previously developed novel model. This model treats the porous heat reservoir as an equivalent porous medium of a single porosity. However, it considers local thermal non-equilibrium between solid rock matrix and fluid flowing in the factures and employs two energy conservation equations to describe heat transfer in the rock matrix and in the fractures, respectively, enabling the modeling and analyses of convective heat exchange in the heat reservoir. Another salient feature of this model is its capability of simulating the complete subsurface heat exchange process in EGS. The EGS subsurface geometry of interest physically consists of multiple domains： open channels for injection and production wells, the artificial heat reservoir, and the rocks enclosing the heat reservoir, while computationally we treat it as a single-domain of multiple sub-regions associated with different sets of characteristic properties （porosity and permeability, etc.）. This circumvents typical difficulties about matching boundary conditions between sub-domains in traditional multi-domain approaches and facilitates numerical implementation and simulation of the complete subsurface heat exchange process. This model is used to perform a comprehensive parametric study with respect to an imaginary doublet EGS. Effects of several parameters, including the permeability of heat reservoir, heat exchange coefficient in the heat reservoir, the specific area of fractures in the heat reservoir, and thermal compensation from surrounding rocks, on the heat extraction efficiency and EGS lifetime are analyzed.
文摘Present study describes the results of an efficient protocol for the isolation of good quality DNA from human saliva. The protocol includes collection of saliva in sterile specimen tubes, followed by the cell lysis. After formation of cell lysate, proteins wereextracted by phenol chloroform treatment for purification of DNA. The purified DNA was precipitated by adding equal volume of isopropanol to the treated supernatant. After isolation DNA pellet was washed with 70% ethanol, air-dried and was suspended in 30 pL of double distilled water. Best quality of DNA was extracted from the saliva samples and the PCR product was amplified for hyper-variable regions （HVI＆ HV2） of the mitochondrial DNA. The genes were cleaned with GeneAll gel elution kit （Gel SV） （Cat. No. 102-10） and sequenced accordingly. The DNA isolation protocol presented here is recommended for the isolation, best quality and yield of DNA from the human saliva.
基金supported by National Key Basic Research Programs of China (Grant No. 2012CB956100)the National Natural Science Foundation of China (Grant Nos. 41072120 & 41321061)
文摘Sedimentary pigments are useful proxy indicators of phytoplankton biomass, community structure, primary productivity and human influence in lacustrine and oceanic ecosystems. Pigments are relatively labile due to their complex chemical structures, which makes the extraction and analysis of sedimentary pigments challenging. In addition, it is important to select appropriate methods to study sedimentary pigments in regions which lack previous investigations. In this study, we adopted the L9（34） orthogonal design to develop methods of extraction and HPLC （high performance liquid chromatography） analysis of sedimentary pigments at two lakes on the Tibetan Plateau： meromictic lake-Dagze Co and dimictic lake-Jiang Co. The orthogonal design comprises 9 combinations of various parameters for extraction and HPLC analysis. The results show that the type and volume of solvent are the most important factors for pigment extraction, and the mobile phase and column selection are the most important for HPLC analysis. For the study sites, we found that the best methods to extract sedimentary pigments are as follows： the use of a mixture of acetone：methanol：water （80： 15：5, v：v：v） as the extraction solvent; sol- vent/sample ratio of 10 mL/g; sonication for 30 s and standing extraction for 6 h. The best methods for HPLC analysis are as follows： Zorbax Eclipse plus C8 column with mobile phase A, methanol：acetonitrile：0.25 M aqueous pyridine （50： 25：25, v ： v ： v） and mobile phase B, methanol： acetonitrile： acetone （20： 60： 20, v： v： v）; pH of mobile phase A adjusted to 6 with acetic acid; and HPLC column temperature maintained at 40~C. The study provides an experimental basis for future investigations of past changes in primary productivity and the response of lake ecosystems to climate change and human activities on the Tibetan Plateau.
