Dust distribution in open-pit mines based on monitoring data and fluent simulation.

To understand the concentration and distribution of PM2.5 and PM10 in open-pit mines, a beta-ray particle monitor and some laser monitors were arranged in Haerwusu Surface Coal Mine (HSCM), Inner Mongolia, China. A fluent simulation was made to study the dust move in the pit and escape rate and time out of the pit. The main conclusions include (1) in HSCM, the concentration of PM10 changes with that of PM2.5, meeting the power function PM10 = 2.548 × PM2.50.993. The dust concentration around the working mining equipment is very high. For example, around a working drill, the PM2.5 can be up to 426 µg/m3, and around a working power shovel, the PM2.5 can be up to 352 µg/m3. (2) At the same time, the PM2.5 concentration is nearly equal throughout the pit, away from the operating equipment, with a confidence level of 95%. The mean dust concentration away from the equipment is 76.7 µg/m3 when this mining equipment is working. So, the number of monitors in the pit can be decreased without affecting the quality of dust monitoring, which means that the cost of monitoring can be cut down. (3) Base on Fluent simulation results, the average escape time of dust particles with different diameters is similar, but the maximum escape time decreases as the particle diameter increases, which means that most dust moves with the air swirl, but some smaller dust particles can hang in the pit for a longer time. Also, the escape rate decreases rapidly as the diameter of the dust increases. (4) Dust is rotated and diffused evenly in the pit under the action of the eddy current in the pit. Finally, when the dust is swirled to a higher level than that of the pit head, the dust can escape out of the pit.

Effect of ulinastatin on postoperative immune function of effective and regulatory T-lymphocytes in peripheral blood in patients undergoing laparoscopic operation / 中华麻醉学杂志

Objective To investigate the effect of ulinastatin on the postoperative immune function of effective T-lymphocytes (Teff cells) and regulatory T-lymphocytes (Treg cells) in the peripheral blood in patients undergoing laparoscopic operation.Methods Forty ASA physical status Ⅰ or Ⅱ patients,aged 20-40 yr,weighing 45-65 kg,scheduled for elective laparoscopic operation for infertility,were equally and randomly divided into 2 groups using a random number table:control group (group C) and ulinastatin group (group U).At 15 min before induction of anesthesia,ulinastatin 200,000 U (in 100 ml of normal saline) was infused intravenously in group U,while the equal volume of normal saline was infused instead in group C.Anesthesia was induced with iv injection of fentanyl,propofol,and cisatracurium and maintained with iv infusion of propofol and sevoflurane.Before surgery (T0),at the end of surgery (T1) and on 1st and 3rd days after surgery (T2.3),venous blood samples were collected from the peripheral blood for determination of the expression of Teff cells (CD4 + CD25-) and Treg cells (CD4 + CD25+) and serum interferon-γ (IFN-γ) and transforming growth factor-β (TGF-β) concentrations (by ILISA).Teff/Treg and IFN-γ/TGF-β ratios were calculated.Results Compared with the baseline value at T0,the expression of Treg cells was significantly up-regulated,and Teff/Treg ratio was decreased at T2 and T3 in group C,and the expression of Teff cells was up-regulated at T3 (P ＜ 0.05 or 0.01),while no significant difference was found in the expression of Treg cells and Teff/Treg ratio at T3 in group U (P ＞ 0.05).Compared with group C,the expression of Teff cells was significantly up-regulated at T3,the expression of Treg cells was down-regulated and Teff/Treg ratio was increased at T2 and T3,the concentration of serum TGF-β was decreased and IFN-γ/TGF-β ratio was increased at T2 and T3 in group U (P ＜ 0.05 or 0.01).No significant changes were found in the serum IFN-γ and TGF-β concentrations and IFN-γ/TGF-β ratio at each time point in the two groups (P ＞ 0.05).Conclusion Ulinastatin can enhance the immune function of Teff cells in the peripheral blood and decrease the immune function of Treg cells,thus maintaining the balance of the postoperative cellular immune function in patients undergoing laparoscopic operation.

Effect of pregnancy on potency of bupivacaine for spinal anesthesia in rats / 中华麻醉学杂志

Objective To investigate the effect of pregnancy on the potency of bupivacaine for spinal anesthesia in rats. Methods Female non-pregnant SD rats weighing 180-220 g and 17 day pregnant SD rats weighing 350-400 g were used in this study. The rats ( 18 non-pregnant, 18 pregnant) in which PE-10 catheter were successfully placed without complications were selected. The 18 non-pregnant rats were randomly divided into 3 groups (n =6 each): control group (group C), 2% bupivacaine group (group B2 ) and 4% bupivacaine group (group B4). The 18 pregnant rats were also randomly divided into 3 groups (n = 6 each): control group (group PC),2% bupivacaine group (group PB2 ) and 4% bupivacaine group (group PB4 ). Group C and PC received intrathecal (IT) normal saline 30 μl, and the other 4 groups received 2% or 4% bupivacaine 30 μl intrathecally. Analgesia was determined using the taifllick latency (TFL) before IT administration (baseline), and at 10 min, 20 min,30 min, 1 h, 2 h, 4 h, 1 d, 2 d, 3 d and 4 d after IT administtation. The percentage of the maximal possible effect (MPE) was calculated. Hind-limb motor function (MF) was also assessed. Results Compared with the baseline value, MPE at 10 min-2 h after administration and MF scores at 10 min-1 h after administration were significantly increased in group B2, MPE at 10 min-4 h after administration and MF scores at 10 min-1 h after administration were significantly increased in group B4;MPE at 10 min-1 d after administration and MF scores at 10 min2 h were significantly increased in group PB2 and MPE at 10 min-1 d after administration and MF scores at 10 min4 h were significantly increased in group PB4 ( P ＜ 0.05 ). Conclusion Pregnancy can enhance the potency of bupivacaine for spinal anesthesia in rats.