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991.
A new multi‐stacking pre‐concentration procedure based on field‐enhanced sample injection (FESI), field‐amplified sample stacking, and transient isotachophoresis was developed and implemented in a compact microchip electrophoresis (MCE) with a double T‐junction glass chip, coupled with an on‐chip capacitively coupled contactless conductivity detection (C4D) system. A mixture of the cationic target analyte and the terminating electrolyte (TE) from the two sample reservoirs was injected under FESI conditions within the two sample‐loading channels. At the double T‐junction, the stacked analyte zones were further concentrated under field‐amplified stacking conditions and then subsequently focused by transient‐isotachophoresis and separated along the separation channels. The proposed multi‐stacking strategy was verified under a Universal Serial Bus (USB) fluorescence microscope employing Rhodamine 6G as the model analyte. This developed approach was subsequently used to monitor the target quinine present in human plasma samples. The total analysis time for quinine was approximately 200 s with a sensitivity enhancement factor of approximately 61 when compared to the typical gated injection. The detection and quantification limits of the developed approach for quinine were 3.0 μg/mL and 10 μg/mL, respectively, with intraday and interday repeatability (%RSDs, n = 5) of 3.6 and 4.4%. Recoveries in spiked human plasma were 98.1–99.8%. 相似文献
992.
It is a common practice in insulator‐based dielectrophoretic separation to use and reuse PDMS‐constructed microdevice for an extended period of time while performing biological and technical replicate experiments. This is usually done to rule out any effects of device variation on separation efficiency. Ensuring that all experimental conditions remain the same is critical to the conclusion that can be drawn from such repeated experiments. One important contributing factor to the flow of materials within the device is electro‐osmotic velocity, which stems from the surface condition of the device construction materials. In this paper, we present an affordable microwave‐based (MESA‐Mgen) oxygen plasma cleaner developed for approximately less than $100 using readily obtainable parts from an average local hardware store with no specialized tools. This low‐cost room‐air microwave plasma generator was designed using an R‐4055, 400 W, 2450 MHz half‐pint household microwave oven (Sharp ® ) for exploring the possibility of sealing polydimethylsiloxane (PDMS) devices onto glass with minimal budgetary commitment. Microfluidic channels generated using MESA‐Mgen were evaluated for their electro‐osmotic velocities while factors including contact angles, storage‐solvent, half‐way hydrophobicity period were also explored with MESA‐Mgen, and the results were compared to those obtained from the commercially available plasma cleaner (COM‐PC). These outcomes revealed that the MESA‐Mgen induced hydrophilicity and ensured leak‐free sealing of PDMS substrates in a manner comparable with the COM‐PC. 相似文献
993.
A method for determining local inhomogeneities of the rotating plasmas is proposed. This method is based on spectral and correlation analysis of the reflected signals from the plasma at normal and oblique microwave incidence. Experimental approbation of the method is made. 相似文献
994.
�����죬���������� ���ӹ�ǿ��л�Ǻ죬���������� ������ ������ �������� 《核聚变与等离子体物理》2018,38(3):249-253
为了判断中性束注入加热效果和研究等离子体宏观旋转和有效电荷数(Zeff)对中子出射的影响,结合实验数据,利用TRANSP模拟程序研究了EAST中性束注入加热时,等离子体旋转速度、有效电荷数Zeff以及等离子体储能与中子出射率的关系。模拟结果表明,在能量为65keV、功率为2.89MW的中性束注入加热时,等离子体产生较大的旋转,旋转减少快离子热化时间,降低中子产额;有效电荷数Zeff增加时,快离子投掷角散射增强,束靶反应减少,中子产额缩减。中子出射率随等离子体储能的增加而增加。 相似文献
995.
A sensitive analytical method was developed to determine tetrodotoxin(TTX) in human plasma samples using protein precipitation, followed by ultra performance liquid chromatography(UPLC) analysis coupled with tandem mass spectrometry(MS/MS) using 11-deoxytetrodotoxin(11-deoxyTTX) as an internal standard. The plasma samples were prepared using protein precipitation prior to being analyzed by UPLC-MS/MS to identify TTX over a zwitterionic-hydrophilic interaction liquid chromatography column. The retention time values of TTX and 11-deoxyTTX were 4.12 and 3.67 min, respectively. TTX and 11-deoxyTTX were monitored and quantitated on the basis of their ion transitions for their respective precursor ions to their product ions(i.e., m/z 320.0→162.1 for TTX and m/z 304.0→176.0 for 11-deoxyTTX) in the multiple reaction-monitoring mode. The lower limit of quantification of this method was determined to be 0.0199 ng/mL. This method showed good linearity for plasma samples that contained TTX concentrations in the range of 0.0199-1.99 ng/mL. The specificity, precision, accuracy, matrix effect, and stability characteristics of this method were also examined. The intra-assay precision and accuracy ranged from 1.89% to 6.00% and from 92.21% to 100.00%, whereas the inter-assay precision and accuracy ranged from 0.64% to 7.75% and from 99.38% to 101.26%, respectively. This new method therefore represents a rapid, accurate, reliable, and highly sensitive method for the qualitative and quantitative analyses of a trace amount of TTX in human plasma samples. 相似文献
996.
Ram Niranjan R.K. Rout B.S. Tomar P.S. Ramanjaneyulu D.B. Paranjape T.C. Kaushik 《Physics letters. A》2018,382(46):3365-3368
Pulsed neutrons generated in a plasma focus device are used for the thermal neutron activation analysis (TNAA) of selected three elements having widely different half-lives varying from a few seconds to a few days [Dysprosium (Dy), Manganese (Mn) and Gold (Au)]. Neutron pulse having strength of neutrons/pulse with a pulse width of is produced by “MEPF-12” device operated at a filling gas (deuterium + 0.5% krypton) pressure of 3 mbar. The fast 2.45 MeV D–D neutrons are thermalized before irradiating the sample. The decay gammas from the radioisotopes 165mDy (), 56Mn (), and 198Au () produced via reactions, 164Dy()165mDy, 55Mn() 56Mn, and 197Au() 198Au respectively are counted off-line in a lead shielded well type NaI(Tl) detector coupled to a calibrated 2048 channel analyzer. The values of half-lives evaluated from the measured decay gammas, , and respectively for the radioisotopes of Dy, Mn and Au, are seen to be close to the values reported in literature. 相似文献
997.
998.
计算了常压下3 000~25 000 K范围内熔化极气体保护焊(GMAW)保护气体Ar,CO2,82%Ar-18%CO2及其与Fe蒸汽的混合物的平衡成分。上述气体被看作一种Ar-CO2-Fe等离子体,等离子体中的39种粒子被分为5种主元粒子和34种非主元粒子。根据化学方程,非主元粒子由主元粒子表示以减少未知数的个数和求解量,再利用牛顿迭代法对平衡方程进行求解,最终实现了成分求解。计算结果表明,Ar气随着温度升高依次发生一次电离和二次电离,CO2气体除了在高温时发生原子电离外,在低温时(T<8 000 K)还存在CO2,O2,CO等分子的解离,82%Ar-18%CO2混合气则既有解离又有电离。Fe的加入会增加等离子体的电子密度,特别是在15 000 K以下。等离子体成分的确定为GMAW电弧等离子体辐射属性计算以及电弧中Fe蒸汽浓度的光谱测定奠定了基础。 相似文献
999.
用激光诱导击穿光谱技术比较土豆和百合中的微量元素 总被引:3,自引:0,他引:3
激光诱导击穿光谱(LIBS)已成功地运用于固体、液体、气体样品中微量元素的测量以及微生物、细菌等的鉴别分析上,而在植物样品上面的应用则是一个较新的课题。该实验用纳秒Nd∶YAG激光器击穿真空冻干的土豆、百合样品,用光纤光谱仪测量了其LIBS光谱。通过鉴别、分析LIBS光谱,得到了这两种样品中微量元素的成分。并且对土豆干和百合干中Ca,Na,K,Fe,Al,Mg六种金属元素典型谱线的强度进行了统计分析,并由此得到了样品中这六种微量元素含量的对比情况。实验结果表明土豆干中的Ca和Na等含量都明显高于百合干,而百合干中Mg的含量较高。实验结果还表明用LIBS技术检测、对比冻干植物样品中微量元素含量是一种快速、有效的分析方法。 相似文献
1000.
研究了悬浮液雾化进样感耦等离子体原子发射光谱基本参数-等离子体电子密度的测定。实验使用Stark效应常用的谱线Hβ线来计算等离子体电子密度。测定结果表明悬浮液雾化进样同水溶液雾化进样感耦等离子体原子发射光谱时等离子体电子密度没有发生显著的变化,数值基本上为1015数量级。固含量高达10% TiO2悬浮液雾化进样等离子体原子发射光谱,电子密度测定结果仅有微小的降低。高固含量悬浮液雾化进样等离子体原子发射光谱没有显著地影响等离子体电子密度,有助于使用高固含量悬浮液雾化进样等离子体原子发射光谱来进行痕量元素分析测定。 相似文献