纳秒脉冲液相放电耦合微气泡固氮影响因素分析

由气液等离子体放电产生的活化水富含活性氧和活性氮(NO_(2)^(-)、NO_(3)^(-)、H_(2)O_(2)、O_(3)等),在环境治理、材料合成和医疗卫生等领域有着广泛的应用前景。该文提出了一种“多微孔-同轴式”的微气泡等离子体放电结构,微孔和微气泡的引入降低了在液相中的击穿场强,并且微气泡增加了气液界面的化学反应和活性物质的溶解。以空气为放电气体,主要探究了正、负极性脉冲参数对活化水固氮特性的影响。此外,还考察了气体流速、温度等因素对活化水中的氮特性的影响,并诊断了电学特性。结果表明,正极性放电下NO_(2)^(-)产量和NO_(3)^(-)产量分别为7.2 mg、28.8 mg,相比负极性放电分别高出0.43 mg、3 mg,经计算正极性放电能量效率高达15.02 g/(kW·h)。同时研究发现,当气流流速为2 L/min时,固氮性能最佳;水温越高,氮含量会随着液相分解动力学温度的降低而减弱。

Comparison of discharge characteristics and methylene blue degradation through a direct-current excited plasma jet with air and oxygen used as working gases

Through using a direct-current driven plasma jet operated underwater,degradation of methylene blue(MB)is investigated with air and oxygen used as working gases.With a low power voltage,a plasma plume extends from the needle electrode,which is purple in air.It turns pink after it bridges the two electrodes.During the process,oxygen plasma remains white.Discharge operates in a pulsed mode or a continuous one,which depends on the magnitude of power voltage.For the pulsed mode,oxygen discharge has a shorter plume and a higher pulse frequency than air discharge under the same power voltage.For the same current of the continuous mode,both power and gap voltages of oxygen discharge are higher than those of air discharge.Moreover,MB degradation efficiency increases with increasing power voltage or initial concentration of MB solution.Compared with air discharge,oxygen discharge has a higher degradation efficiency with the same power voltage and treatment time.The pulsed oxygen discharge with power voltage of about 6.5 k V has the highest efficiency in degrading MB dye,reaching approximately 85.8%after 10 min treatment.As a comparison,after 10 min treatment in air discharge,the highest degradation efficiency is 63.7%,which appears in the continuous mode at a power voltage of 10.6 kV.Besides,optical spectra from the discharges are also compared for the two types of working gases.

附子理中汤及其加减方对溃疡性结肠炎疗效的系统评价

目的对附子理中汤及其加减方治疗溃疡性结肠炎的疗效进行系统评价,并总结其治疗溃疡性结肠炎的临床疗效及安全性。方法按照Cochrane系统评价的方法,在CNKI、VIP、万方数据以及Pub Med、EMBase、Medline、Cochrane Library等数据库中检索文献,查找应用附子理中汤及其加减方治疗溃疡性结肠炎的随机对照试验和半随机对照试验。经过筛选纳入符合条件的临床随机对照试验(randomized controlled trail,RCT),对所纳入的研究进行数据提取和质量评价后,应用Rev Man 5. 3软件进行Meta分析,应用GRADE系统对证据质量和等级推荐进行评分。结果一共纳入8项符合条件的RCT研究,共有688名患者参加符合条件的临床研究,但这8项研究方法学质量均较差。Meta分析结果显示:总有效率OR合并=4. 32 [OR=4. 32,95%CI (2. 55,7. 31),P <0. 000 01]。GRADE系统评价结果显示,证据水平均为B,推荐等级为弱推荐。结论采用附子理中汤及其加减方治疗溃疡性结肠炎有效率高于单纯西药治疗,且有较高的安全性,无明显的不良反应。由于纳入的临床对照研究质量有不足,所以附子理中汤及其加减方治疗溃疡性结肠炎的疗效尚不能做出最后的结论,仍然需要更多高质量的RCT才能得出肯定的结论。