Determination of Key Technical Parameters in the Study of New Pressure Sealing Technology for Coal Seam Gas Extraction.

Coal is affected by the concentrated stress disturbance of mining, the disturbance of drilling hole formation, and the concentrated stress of coal shrinkage and splitting of gas desorption from the hole wall; these result in a large number of secondary cracks that collect and leak gas. As a result, it is difficult for the coal seam sealing process to meet engineering quality sealing requirements, which results in problems such as low gas concentration during the extraction process. In this paper, based on the analysis of coal pore and fissure characteristics, and in view of the current situation of gas drainage and sealing in this coal seam, combined with the existing grouting and sealing technology, it is proposed to use pressure grouting and sealing to realize the sealing of deep coal bodies in the hole wall. According to the field conditions, the experimental pressure sealing parameter index is as follows: theoretical sealing length L1 = 9.69 m, the sealing length L2 = 13.98 m is verified, and the final sealing length is determined to be 15 m; the sealing radius is determined to be 0.6 m; the cement slurry was prepared on site with a water: cement ratio of 2:1; PG = 0.43 MPa was calculated; the range of the slurry diffusion radius R was 93.4-176.6 cm; the grouting pressure was determined to be 0.516 MPa. Field application practice has proved that: (1) Under the same drilling parameters and sealing parameters, the gas drainage effect of drilling with pressure sealing is 2.3 times higher than that without pressure sealing; (2) Using traditional sealing technology for drilling holes, the gas extraction concentration is far lower than the sealing operation effect of using the pressure sealing process; (3) Reasonably extending the length of the gas extraction drilling and sealing is a basic guarantee for realizing a substantial increase in the gas extraction concentration; (4) Sealing with pressure leads to a reliable and stable hole process.

Simple and sensitive colorimetric sensors for the selective detection of Cu(ii).

A simple, sensitive colorimetric probe for detecting Cu(ii) ions with fast response has been established with a detection limit of 2.82 µM. UV-Vis spectroscopy along with metal ion response, selectivity, stoichiometry, competition was investigated. In the presence of copper(ii), the UV-Vis spectrum data showed significant changes and the colorimetric detection showed a color change from colorless to yellow. After the selective binding of receptor L with Cu(ii), the UV-visible absorption at 355 nm decreased dramatically, a new absorbance band appeared at 398 nm and its intensity enhanced with the increase in the amount of Cu(ii). Moreover, it exhibited highly selective and sensitive recognition towards Cu(ii) ions in the presence of other cations over the pH range of 7-11. The complex structure was verified by FT-IR spectroscopy, elemental analysis and quantum mechanical calculations using B3LYP/6-31G(d) to illustrate the complex formation between L and Cu(ii). According to the Job plot and the quantum mechanical calculations, the stoichiometric ratio for the complex formation was proposed to be 1 : 1.

Malignant gliomas induce and exploit astrocytic mesenchymal-like transition by activating canonical Wnt/ß-catenin signaling.

The complex microenvironment of malignant gliomas plays a dynamic and usually cancer-promoting role in glioma progression. Astrocytes, the major stromal cells in the brain, can be activated by glioma microenvironment, resulting in a layer of reactive astrocytes surrounding the gliomas. Reactive astrocytes are universally characterized with the upregulation of glial fibrillary protein and glycoprotein podoplanin. In this work, we investigated the role of reactive astrocytes on malignant glioma microenvironment and the potential mechanism by which glioma cells activated the tumor-associated astrocytes (TAAs). The reactive astrocytes were observed around gliomas in the intracranial syngeneic implantation of rat C6 and mouse GL261 glioma cells in vivo, as well as primary astrocytes cultured with glioma cells condition medium in vitro. Besides, reactive astrocytes exhibited distinct epithelial-to-mesenchymal (-like) transition and enhanced migration and invasion activity, with the decrease of E-cadherin and concomitant increase of vimentin and matrix metalloproteinases. Furthermore, canonical Wnt/ß-catenin signaling was activated in TAAs. The Wnt/ß-catenin pathway inhibitor XAV939 and ß-catenin plasmid were used to verify the regulation of Wnt/ß-catenin signaling on TAAs and their invasion ability. Taken together, our findings established that glioma cells remarkably activated astrocytes via upregulating Wnt/ß-catenin signaling, with obviously mesenchymal-like transition and increased migration and invasion ability, indicating that glioma cells may stimulate adjacent astrocytes to degrade extracellular matrix and thereby promoting tumor invasiveness.