Influencing factors analysis of hard limestone reformation and strength weakening under acidic effect

Roof disaster has always been an important factor restricting coal mine safety production.Acidic effect can reform the rock mass structure to weaken the macroscopic strength characteristics,which is an effective way to control the hard limestone roof.In this study,the effects of various factors on the reaction characteristics and mechanical properties of limestone were analyzed.The results show that the acid with stronger hydrogen production capacity after ionization(pK_(a)<0)has more prominent damage to the mineral grains of limestone.When pKa increases from−8.00 to 15.70,uniaxial compressive strength and elastic modulus of limestone increase by 117.22%and 75.98%.The influence of acid concentration is manifested in the dissolution behavior of mineral crystals,the crystal defects caused by large-scale acid action will lead to the deterioration of limestone strength,and the strength after 15%concentration reformation can be reduced by 59.42%.The effect of acidification time on limestone has stages and is the most obvious in the initial metathesis reaction stage(within 60 min).The key to the strength damage of acidified limestone is the participation of hydrogen ions in the reaction system.Based on the analytic hierarchy process method,the influence weights of acid type,acid concentration and acidification time on strength are 24.30%,59.54% and 16.16%,respectively.The research results provide theoretical support for the acidification control of hard limestone roofs in coal mines.

新型负载异烟肼海藻酸钠-壳聚糖微球体内安全性及黏附性研究

目的探讨负载异烟肼(INH)的海藻酸钠-壳聚糖微球(SCMI)在大鼠体内的安全性,以及在气管和肺组织中的粘附性。方法将24只雄性SD大鼠随机分为对照组(NC组)、INH组、SCMI组,每组各8只。通过HE染色观察各组大鼠肝、肾及肺组织病理学改变。通过酶联免疫吸附试验检测大鼠肺泡灌洗液炎症因子白细胞介素(IL)-1β、IL-6及肿瘤坏死因子-α(TNF-α)的水平。检测血液中白细胞(WBC)、淋巴细胞(LYMPH)、红细胞(RBC)、血红蛋白(Hb)、血小板(PLT)、谷草转氨酶(AST)、谷丙转氨酶(ALT)、碱性磷酸酶(ALP)、总胆红素(TBiL)、总蛋白(TSP)、肌酐(Cr)及尿素氮(BUN)的水平。观察大鼠体质量变化,评估SCMI在大鼠体内的安全性。将28只大鼠气管内给予荧光标记的SCMI溶液,观察SCMI在气管及肺组织中的粘附性。结果气管给药后第7天,INH组大鼠的体质量低于NC组与SCMI组,差异有统计学意义(P<0.05)。INH组大鼠肺组织IL-1β、IL-6、TNF-α表达水平高于NC组与SCMI组,差异均有统计学意义(P<0.05)。各组大鼠WBC、LYMPH、RBC、Hb、PLT、AST、ALT、ALP、TBiL、TSP、Cr、BUN比较,差异均无统计学意义(P>0.05)。给药12 h时,大鼠肺叶组织中可见大量荧光标记,提示12 h内SCMI即可广泛分布于肺叶中;48 h时观察到大量荧光标记,提示气管局部给予SCMI 48 h后仍能大量粘附于肺叶上。结论SCMI增加了INH在大鼠体内的粘附,且在气管局部给药中表现出良好的安全性,是INH局部给药的良好载体。