共查询到10条相似文献,搜索用时 93 毫秒
1.
离子引出过程是原子蒸气激光同位素分离中非常重要的物理过程之一,而其中关键的等离子体参数(等离子体初始密度和电子温度等)均会对离子引出特性产生影响.基于千赫兹电源驱动的氩气高压交流放电等离子体射流源,建立了离子引出模拟实验平台-2015 (IEX-2015),开发了用于诊断氩等离子体参数的"碰撞-辐射"模型,对等离子体射流区的电子温度和电子数密度等关键参数进行了测量.结果表明,电源输入功率和驱动频率以及工作气体流量均会对等离子体射流区的电子温度和数密度产生影响;在真空腔压强为10~(-2)Pa量级下,射流区电子数密度和电子温度的可调参数范围分别为10~9—10~(11)cm~(-3)和1.7—2.8 e V,这与实际离子引出过程中的等离子体参数范围相近.在此基础上,开展了不同引出电压、极板间距和电子数密度条件下初步的离子引出实验,所得到的离子引出电流变化规律亦与实际原子蒸气激光同位素分离中的离子引出特性定性一致.上述研究结果验证了在IEX-2015上开展离子引出模拟实验的可行性,为后续深入开展离子引出特性的实验研究准备了良好的条件. 相似文献
2.
采用正交试验法,对板蓝根靛玉红超临界CO2萃取工艺进行优化。选用萃取温度、萃取压力、萃取时间作为正交试验的3个因素,每个因素选3个水平,以提取物中靛玉红的含量来确定最佳提取条件,并且在最佳条件下确定所加夹带剂的最佳剂量。结果表明最佳工艺为:萃取温度45℃、萃取压力35MPa、萃取时间3h,夹带剂为75%的乙醇200mL。最佳工艺条件下提取靛玉红的得率为4.95μg/g,为传统提取方法的1.6倍。 相似文献
3.
多壁碳纳米管固相微萃取测定水中的三唑酮和噻嗪酮 总被引:1,自引:0,他引:1
将多壁碳纳米管涂在不锈钢丝上制作了固相微萃取探头,利用固相微萃取-气相色谱-质谱联用技术测定湖水中的三唑酮和噻嗪酮。对萃取温度、萃取时间及离子强度等影响萃取效率的因素进行了优化。在优化的条件下,通过加标水样的分析对方法进行了评估。结果表明,方法的线性范围为25—150μg/L,相关系数为0.9922—0.9982,三唑酮和噻嗪酮的检出限(LOD,S/N=3)分别为2.21ng/L和0.18ng/L。湖水的加标回收率在84%—110%之间,相对标准偏差小于10.8%。 相似文献
4.
5.
Ultrasound-assisted extraction of ginseng saponins from ginseng roots and cultured ginseng cells 总被引:11,自引:0,他引:11
Ultrasound-assisted extraction was evaluated as a simpler and more effective alternative to conventional extraction methods for the isolation of ginsenosides (saponins) from various types of ginseng. The ginseng samples were extracted with different solvents, under either direct sonication by an ultrasound probe horn or indirect sonication in an ultrasound cleaning bath. The ultrasonic extraction was compared with the conventional method of refluxing boiling solvents in a soxhlet extractor, on the yields of both the total saponin isolated by thin-layer chromatography and the individual ginsenosides by high performance liquid chromatography. It was found that the sonication-assisted extraction of ginseng saponins was about three times faster than the traditional extraction method. The ultrasonic extraction was not only more efficient but also convenient for the recovery and purification of the active ingredients of plant materials. In addition, the sonication-assisted extraction can be carried out at lower temperatures which are favorable for the thermally unstable compounds. 相似文献
6.
Ultrasonically assisted acid extraction of manganese from slag 总被引:5,自引:0,他引:5
An ultrasonically assisted extraction (UAE) technique was developed for the extraction of manganese from electrolytic manganese slag using a sulfuric acid-hydrochloric acid mixture (4:0.3, v/v) as solvent. The UAE conditions were optimized and the significance of variables affecting UAE tested. The determination of manganese was carried out by atomic absorption spectrophotometry (AAS). The ultrasonic extraction efficiency of manganese can reach about 90% under the following optimum conditions: solvent-slag ratio: 4 mL/g; temperature: 333 K; particle size: 0.2 mm; extraction time: 35 min; amount of additive (citric acid): 8 mg/g slag. During the UAE process, the particle size parameter on the extraction was the most significant, followed by solvent-slag ratio, citric acid mass, time and temperature. The repeatability of UAE technique was satisfactory. The ultrasonic method shown to be a much superior approach to the conventional extraction method in the extraction of manganese from slag. 相似文献
7.
Potential for the use of ultrasound in the extraction of antioxidants from Rosmarinus officinalis for the food and pharmaceutical industry 总被引:7,自引:0,他引:7
Ultrasound was used to increase the extraction efficiency of carnosic acid from the herb Rosmarinus officinalis using butanone, ethyl acetate and ethanol as solvents. Both dried and fresh leaves of the herb were extracted and, when performed at the same temperature, sonication improved the yields of carnosic acid for all three solvents and shortened the extraction times. Sonication also reduced the solvent effect so that ethanol, which is a poor solvent under conventional conditions, reached a similar level of extraction efficiency to the other two when sonicated. The extraction of dried herb with ethanol proved to be more efficient than that of fresh material, probably due to the water present in the latter. 相似文献
8.
9.
Ultrasound-assisted extraction of xyloglucan from apple pomace 总被引:2,自引:0,他引:2
Ultrasound-assisted extraction was evaluated as a simpler and more effective alternative to conventional extraction method for the isolation of xyloglucan from apple pomace. The apple pomace samples were extracted under indirect sonication in an ultrasound cleaning bath. The ultrasound extraction was compared with the conventional method, on the productions of xyloglucan. It was found that the ultrasound-assisted extraction of xyloglucan was about three times faster than the traditional extraction method. Response surface methodology was employed to study the effect of liquid:solid ratio, KOH concentration and ultrasound-assisted extraction time on the yield of xyloglucan from apple pomace. Regression analysis was performed on the data obtained. The most relevant variable was the quadratic of liquid:solid ratio. The coefficient determination (R2) was good for the second-order model. The optimum combination was determined as a liquid:solid ratio of 34.4:1 (v/w), a KOH concentration of 3.3 M and an ultrasound-assisted extraction time of 2.5 h. 相似文献
10.
Forsythia suspensa (Thunb.) Vahl is one of the most widely used traditional Chinese medicines, and possesses important biological activities, such as antibacterial, antiviral, anti-inflammatory and antioxidant activities. Phillyrin is the main bioactive component of Forsythia suspensa. In this paper, ultrasound-assisted extraction of phillyrin from Forsythia suspensa was studied with HPLC-photodiode array detection. Effects of several experimental parameters, such as type and concentration of extracting solvent, ratio of liquid to material, extraction temperature, and time of sonication on extraction efficiencies of phillyrin from Forsythia suspensa were evaluated. The optimal extraction conditions were 1g plant sample with 10 ml of 20% methanol and the extraction for 60 min at 60°C under ultrasonic irradiation. Under the optimum conditions, the yield of phillyrin was 0.713±0.009 mg/g. The results indicated that the ultrasound-assisted extraction is a very useful method for the extraction of important phytochemicals from plant materials. 相似文献