Changes in properties of tar obtained during underground coal gasification process

In this study,the composition of tars collected during a six-day underground coal gasification(UCG)test at the experimental mine‘Barbara’in Poland in 2013 was examined.During the test,tar samples were taken every day from the liquid product separator and analysed by the methods used for testing properties of typical coke oven(coal)tar.The obtained results were compared with each other and with the data for coal tar.As gasification progressed,a decreasing trend in the water content and an increasing trend in the ash content were observed.The tars tested were characterized by large changes in the residue after coking and content of parts insoluble in toluene and by smaller fluctuations in the content of parts insoluble in quinoline.All tested samples were characterized by very high distillation losses,while for samples starting from the third day of gasification,a clear decrease in losses was visible.A chromatographic analysis showed that there were no major differences in composition between the tested tars and that none of the tar had a dominant component such as naphthalene in coal tar.The content of polycyclic aromatic hydrocarbons(PAHs)in UCG tars is several times lower than that in coal tar.No light monoaromatic hydrocarbons(benzene,toluene,ethylbenzene and xylenes—BTEX)were found in the analysed tars,which results from the fact that these compounds,due to their high volatility,did not separate from the process gas in the liquid product separator.

Effectiveness and Safety of Moxibustion Robots on Primary Dysmenorrhea:A Randomized Controlled Pilot Trial

Objective To conduct a pilot trial to explore the effectiveness and safety of moxibustion robots in treating primary dysmenorrhea(PD)and evaluate its feasibility in clinic.Methods A total of 70 participants with PD were allocated to either moxibustion robot(MR)group(35 cases)or manual moxibustion(MM)group(35 cases)using computer-generated randomization.One acupoint Guanyuan(CV 4)was selected to receive moxa heat stimulation.Two groups of participants were given 3 menstrual cycles of MM and MR treatment respectively(once a day,5 days a session)and received another 3 menstrual cycles follow-up.The degree of pain was evaluated by short-form McGill pain questionnaire(SF-MPQ)and the symptoms of dysmenorrhea were evaluated by Cox Menstrual Symptom Scale(CMSS).The safety was measured by the occurrence rate of adverse events(AEs),including burns(blisters,red and swollen),itching,bowel changes,menstrual cycle disorder,menorrhagia and fatigue,etc.Results A total of 62 patients completed the trial,32 in MR group and 30 in MM group.Compared with baseline,scores of SF-MPQ and CMSS significantly decreased in both groups(P<0.05),and no significant difference was observed between the two groups in the 3rd and 6th menstrual cycles(P>0.05).The total occurrence rate of AEs in MR group was 2.1%,which was significantly lower than MM group(7.2%,P<0.05).Conclusions MR has the same effect as MM at SF-MPQ and CMSS in patients with PD.However,MR is safer than MM(Trial registration No.ChiCTR1800018236).