Search

In Western China, there are some mining areas with complex geological structure and significant hazards of gas, coal and gas outburst. The outburst hazard not only threatens safety of mine gravely, but also makes it difficult to explore coal resources in some regions. Aiming at the characteristics of the complex structure, poor coal seam permeability and multi-seam mining in the mining area, with the purpose of eliminating the danger of outburst and decreasing the gas content of coal seam, this paper made a systematic research on the mining of the lower distant protective layer, the technology of pressure-relieved gas drainage using surface boreholes and eliminating the potential dangers of coal and gas outburst. By constructed the model of similar materials experiments of stope and numerical simulation, the author studied the depressurization effect of protected coal seam under the mining condition of lower distant protective layer: (1) During extraction of the lower distant layer, the stress of protected layer could be reduced sufficiently, and gas permeability coefficient could be increased substantially, providing favorable condition for gas drainage; (2) As the double protective seam mining,40-50 m area of intake entry and return entry of mining face in protected coal seams is dilated area, which is the proper location of surface boreholes; (3) Repeat depressurization mode is found that the gob of the extracted seam below the gassy one provides a "Buffering Effect" for the overlying coal seam which makes the depressurization of the overlying seam weaken. The results from mechanical model for analysis of the stability of surface borehole are: (1) The greater the difference between the strength of adjacent strata is, the bigger the squeezing and shearing stress in the casing become; (2) Under the condition of leaving the space between the casing and borehole wall, the max shearing stress of casing decreased by 50.8% evenly, and the probability of failure of casing was reduced significantly; (3) The longer the production casing is, the bigger the deflection value is and the greater anti-bending ability the casing gets. Based on the above results, the author designed a structure of surface borehole against shearing and rupturing. There leaves the "buffer spacing" between the cementing casing or borehole wall and the production casing which is whole-tube and screen section was handled by "casing enhancement technology", effectively improving the stability of surface borehole. The law of pressure relief methane drainage using surface borehole is demonstrated: (1) Illustrated the distance from working face to borehole (showing the methane permeability coefficients of overlying coal seam and fractured zone), is the key influencing factor of gas production rate of borehole; (2) Revealed the changing mechanism of "fast increase-slowly decrease" of the gas production rate of borehole during the protective coal seam mining, and determined the best layout parameters of surface boreholes; (3) Built a mathematical model for determining the gas flow rate of overlying coal seam and gob, which can provide a basis of assessment for gas drainage of overlying coal seam; (4) Proposed the method of improving gas drainage form overlying pressure released seams with increasing the lower borehole resistance. The research results mentioned above were carried out in Wulan Coal Mine of Shenhua Group, which show that the effect of eliminating outburst by extracting pressure relieved gas with surface boreholes is remarkable. The pure gas drainage quantity of boreholes in the testing area has totally reached 1 512.96 x 104 m³. The max spacing of borehole near the intake entry and the return entry are 150 m and 169 m respectively. The remaining gas quantities of the protected coal seams are eliminated to 3.63 m³/t and 3.14 m³/t, and the gas drainage rates are 65.8% and 68.0%, respectively, completely eliminating the outburst danger of the coal. [ABSTRACT FROM AUTHOR]

Objective: R6G-ddATP was used as a dideoxy fluorescence substrate to establish the single base end extension (SNaPShot)-gel fluorescence method for the rapid detection of the genotypes of three high-risk human papillomaviruses (HR-HPV) ( HPV 18, HPV 33 and HPV 35) genotypes., Methods: HPV quality control products were used as as samples, and R6G-ddATP dideoxy fluorescence reagent was used as substrate. Firstly, HPV was amplified by using universal primers to obtain the first round of amplified products, which were purified and used as templates for subsequent SNaPShot reactions. Then, specific one-step extension primers were used to perform SNaPShot reaction to generate R6G-fluorescence-labeled DNA extension products. The product was subjected to agarose gel electrophoresis, the results of which were observed under a Gel Imager, and the HPV genotyping was done with different one-step extension primers. Each sample was tested three times and the results were compared with DNA sequencing results., Results: The preferred annealing temperature for SNaPShot reaction is 55 ℃. Three HPV genotypes were examined by R6G-ddATP/SNaPShot gel fluorescence assay under optimal conditions, and the results were consistent with DNA sequencing results., Conclusion: The R6G-ddATP/SNaPShot-gel fluorescence method for the micro-detection methods of three HR-HPV genotypes was successfully established and can be used for rapid detection of HPV genotypes., (Copyright© by Editorial Board of Journal of Sichuan University (Medical Sciences).)

Objective: To investigate the expression of IGF-1 and IGFBP-3 in nonalcoholic fatty steatosis hepatocyte models induced by oleic acid., Method: Nonalcoholic fatty steatosis hepatocyte models induced by oleic acid on immortalized human hepatocyte, Oil red O staining and intracellular triglycerides were detected for observing the situation of IHH cells fatty degeneration. IHH cells were divided into control group, NAFLD group, which the control group cultured in DMEM/F12 medium, NAFLD group were treated with oleic acid, 0.5 mmol/L treatment for 72 h. The expression of mRNA and protein of IGF-1 and IGFBP3 were measured by immunofluorescent staining, Western blot and RT-PCR methods. Between the two groups were compared using the t- test., Results: The steatosis models of the hepatocytes were established successfully with 0.5 mmol/L oleic acid. Lipid droplets were observed through Oil red O staining. The level of hepatocyte TG was increased (275.7+/-27.2) mug/mg from (150.2+/-15.6) mug/mg (t = 21.67, P less than 0.01). Compared with the control group, the mRNA of IGF-1 (0.76+/-0.04 vs 4.82+/-1.51, t = 17.915, P less than 0.01), IGFBP-3 (1.58+/-0.93 vs 5.41+/-1.37, t = 12.893, P less than 0.01) and protein expression of IGF-1 (1.00+/-0.29 vs 2.56+/-0.71, t = 29.17, P less than 0.01), IGFBP-3 (0.65+/-0.36 vs 1.23+/-0.91, t = 32. 12, P less than 0.01) significantly decreased in oleic acid-treated group. The results of immunofluorescence staining also confirm the significantly decreased protein expression of IGF-1 and IGFBP-3 in NAFLD group compared with control group., Conclusion: The expression of IGF-1 and IGFBP-3 decreased in nonalcoholic fatty steatosis hepatocyte models, which will provide the experimental basis for the further study of the mechanism of the limited height of some children with non-alcoholic fatty liver disease in clinical.

Objective: To study the effect of growth hormone (GH) combined with Radix Dipsaci on the body growth and the bone mineral content (BMC) of hypophysectomized rats., Methods: The GH deficiency rats model was established using the hypophysectomized operation through the skull and the throat. Qualified rats were divided into the sham-operation group (n = 15), the negative control group (n = 13), the GH intervention group (n = 13), and the GH combined with Radix Dipsaci group(n = 12). GH (0.25 mg/kg) was subcutaneously injected from the cervical part in the GH intervention group and the GH combined with Radix Dipsaci group at the same time, while equal volume of normal saline was injected to the rest groups. 0.7 mL/100 kg Radix Dipsaci was given by gastrogavage to the GH combined with Radix Dipsaci group at the same time, while equal volume of normal saline was given by gastrogave to the rest groups. The body weight, the tail length, and the body length were measured during the intervention period. Blood was withdrawn after 14-day intervention. The femoral bone and the tibial bone were taken out. The levels of GH, insulin-like growth factor 1 (IGF-1), alkaline phosphatase (ALP), and osteocalcin (OC) were measured. The width of the tibial epiphyseal plate was measured. The bilateral femur bone mineral density (BMD) and BMC were measured using the dual energy X-ray absorptiometry., Results: The body weight, the body length, the length of the femoral bone, the length of the tibial bone, the width of the epiphyseal plate, the levels of the GH, IGF-1, ALP, and OC increased in the GH intervention group and the GH combined with Radix Dipsaci group after 2-week intervention, showing statistical difference when compared with the model group (P < 0.01). But there was no statistical difference in the tail length though it also increased (P > 0.05). There was insignificant difference in the aforesaid indices between the two groups (P > 0.05). Compared with the model group, the BMD of the GH combined with Radix Dipsaci group increased with statistical difference (P < 0.01). Compared with the model group, the BMC of the GH intervention group and the GH combined with Radix Dipsaci group increased with statistical difference (P < 0.01). It was highest in the GH combined with Radix Dipsaci group (P < 0.01)., Conclusions: GH combined with Radix Dipsaci showed unobvious effect on promoting the growth. But it could elevate BMD and BMC, and improve the bone metabolism.

Objective: To establish nonalcoholic fatty liver disease (NAFLD) in young rats, and to investigate the metabolic characteristics of these rats., Methods: Fifteen male and fifteen female SD rats of 3 weeks old were randomly divided into three groups, normal group (N), 20% high fat group (HF1) and 30% high fat group (HF2). All the rats were fed under Specific pathogen Free (SPF) condition for 6 weeks and executed at the end of the 6th week. Body length and weight of each rat as well as their liver weight were measured for calculating Liver Index (LI). ALT, AST, TG, TC, INS, Glu and HOMA-IR in the blood were measured. Liver tissue homogenate was prepared for detecting TG level. The liver section was stained with HE and oil red. The expression of SPEBP-1 and leptin in liver was detected by immunostaining., Results: The typical pathological change of NAFLD was found in the rats of HF groups. In HF2 group, no rats died during the experiment and the degree of fat degeneration is homogeneous. Comparing with those in N group, TC (mmol/L), liver TG (mmol/L) and ALT levels in HF2 group were significantly elevated (2.50+/-0.39 vs 1.82+/-0.43, P less than 0.01; 25.38+/-13.29 vs 12.09+/-9.59, P less than 0.01 and 69.80+/-18.22 vs 48.00+/-10.45, P less than 0.01, respectively). Comparing with those in N group, TG level in HF1 group was significantly decreased (0.17+/-0.10 vs 0.32+/-0.12, P less than 0.05), Glu level in HF1 group was significantly elevated (12.33+/-3.48 vs 8.13+/-2.53, P less than 0.05). There were no significant difference between the results of AST, INS and HOMA-IR among the groups. The expression level of SREBP-1 and leptin increased in HF groups., Conclusion: NAFLD can be induced by 30% high-fat feeding for 6 weeks in young rats, high-fat feeding induces the expression of SREBP-1 and leptin expression and fat synthesis.