Formation of methane hazard in longwall coal mines with increasingly higher production capacity

Increasingly higher hard coal production capacity in Upper Silesian Coal Basin(Poland) in the last two decades led to significant increase of methane hazard occurrence in the workings of exploitation areas.An increase of methane content in the exploited seams and in the surrounding strata, associated with increasing depth of mining, results in higher methane emission into the longwall areas from exploited seams and degassing seams in the mining-induced de-stressed zone. Operational experience gained by the collieries confirms that reducing methane release during longwall operations often requires decreasing operating speed of a shearer in a shift. The paper presents an analysis of the parameters and factors,which have critical influence on the formation of methane hazard in longwall areas with high production capacity.

Misoprostol in labour induction of term pregnancy: a meta-analysis

Data sources Data from published English and Chinese literatures about misoprostol in term labour induction were identified from Medline and CBMdisk (using the search terms “misoprostol” and “labour induction”) before 2001; hand searches of reference lists of original studies and reviews (including meta-analyses) and contact with investigators in this field before 2001. Study selection Studies were included if they had data on misoprostol and labour induction. Altogether 623 articles were found and 124 were admitted, including 19 287 cases. Data extraction Data were collected on efficacy and incidence of side-effects of misoprostol and oxytocin. Data were checked for consistency within the published articles and converted into a standard format for incorporation into a centra l database. Data synthesis The average successful induction rate, rates of caesarean section; incidence of tachysystole, hypertonus of uterus and precipitous labour, and rates of meconium stained amniotic fluid between the misoprostol and oxytocin groups were significantly different (P<0.05). There were no significant differences between the two groups concerning the average interval from the administration of misoprostol and oxytocin to the onset of labour, duration of the total stage of labour, incidence rate of foetal distress, neonatal asphyxia (1-minute Apgar score≤7), post partum haemorrhage or amount of blood loss in postpartum.Conclusions Misoprostol is a superior agent over oxytocin on the induction of term labour, but its application might increase the risk of prec ipitatous labour, abnormal uterine contractions or meconium stained amniotic fluid. Therefore, the doasges and regimens of the agent need further investigation.