Online Separation and Preconcentration of Gold and Palladium on Amidinothiourea Immobilized Glass Bead for Interference-Free Flame Atom Absorption Spectrometry Determination

Amidinothiourea immobilized glass bead (AGB) was applied as the microcolumn packing for the flow-injection online separation and preconcentration of Au(III) and Pd(II) coupled with FAAS determination. The peak-area absorbance (A) and the peak-height absorbance (H) were all used as the evaluating modes. Au(III) and Pd(II) in 0.50 M HCl solution were absorbed onto AGB completely and then eluted into AAS with thiourea solution. Base metal ions with a concentration of 2.0 mg/mL and anions with a concentration of 20.0 mg/mL caused no interference in the determination of Au(III) and Pd(II). The LODs of Au(III) and Pd(II) for a preconcentration time of 60 s with a sampling flow rate of 5.0 mL/min for 0.20 μg/mL of Au(III) and 0.30 μg/mL of Pd(II) were 2.7 and 6.5 ng/mL with the H mode and 4.6 and 10.2 ng/mL with the A mode, respectively. The RSD of seven replicate determinations of 0.20 μg/mL of Au(III) and 0.30 μg/mL of Pd(II) were 0.018 and 0.024 for the H mode and 0.013 and 0.018 for the A mode, respectively. The method was successfully applied to the determination of Au and Pd in real samples. __________ From Zhurnal Analiticheskoi Khimii, Vol. 60, No. 10, 2005, pp. 1023–1029. Original English Text Copyright ? 2005 by Liu, Pu, Su. The text was submitted by the authors in English.     

Effect of microstructure on molecular oxygen permeation through condensed phospholipid monolayers

A method is presented that allows novel measurement of the effect of microstructure on the oxygen permeability of highly condensed, polycrystalline phospholipid monolayers. Oxygen permeability of the polycrystalline shell coating a stationary microbubble is measured directly using an apposing microelectrode in the induced transfer mode and modeling oxygen flux through the shell and intervening aqueous medium. Varying cooling rate through the phospholipid main phase transition permits control of shell microstructure by manipulation of crystalline domain size and shape. Domain boundary density, defined as the ratio of the mean domain perimeter to the mean domain area, of the microbubble shell is determined by fluorescence microscopy. Oxygen permeability was shown to increase linearly with domain boundary density at a constant phospholipid acyl chain length and, accordingly, was shown to decrease exponentially with increasing chain length at a constant domain boundary density. Modification of the energy barrier theory to account for microstructural effects, in terms of the domain boundary density, provides a general equation to model passive transport through polycrystalline monolayer films. Results from this method show promise in determining the gas transport kinetics of medical microbubbles and the gas exchange characteristics of biological monolayers.     

OX2(X=F，Cl，Br，I，At)中的离域π63键

本文在理论层面上研究了OX₂(X=F,Cl,Br,I,At)分子的电子结构,结果表明其中存在离域π⁶₃键,氧原子采取sp²杂化方式,与价层电子对互斥理论预测的结果不符. 提出了离域稳定化能衡量形成离域π⁶₃键对能量降低的贡献,证实离域π⁶₃键对分子结构起到了额外的稳定作用. 这些现象可以总结为一种配位效应.     

等离子体破裂期间电流猝灭特征研究

等离子体破裂会对托卡马克装置的安全运行造成严重威胁.等离子体破裂期间电流猝灭速率与电磁负载的大小及逃逸电流平台的形成都密切相关.本文对HL-2A装置等离子体破裂进行了统计分析,统计选用等离子电流的两个衰减区间90%-10%和80%-20%.分析结果表明:HL-2A装置等离子体破裂有四种不同的电流猝灭波形,两个衰减区间最小电流猝灭时间的参数区分别为2.6 ms和2.2 ms,并且不同衰减区间下平均电流猝灭时间统计分布明显不同.     

Coherent beam combination of adaptive fiber laser array with tilt-tip and phase-locking control

We present an experimental study on tilt-tip(TT) and phase-locking(PL) control in a coherent beam combination(CBC) system of adaptive fiber laser array.The TT control is performed using the adaptive fiber-optics collimator(AFOC),and the PL control is realized by the phase modulator(PM).Cascaded and simultaneous controls of TT and PL using stochastic parallel gradient descent(SPGD) algorithm are investigated in this paper.Two-fiber-laser-,four-fiber-laser-,and six-fiber-laser-arrays are employed to study the TT and PL control.In the cascaded control system,only one high-speed CMOS camera is used to collect beam data and a computer is used as the controller.In a simultaneous control system one high-speed CMOS camera and one photonic detector(PD) are employed,and a computer and a control circuit based on field programmable gate array(FPGA) are used as the controllers.Experimental results reveal that both cascaded and simultaneous controls of TT using AFOC and PL using PM in fiber laser array are feasible and effective.Cascaded control is more effective in static control situation and simultaneous control can be applied to the dynamic control system directly.The control signals of simultaneous PL and TT disturb each other obviously and TT and PL control may compete with each other,so the control effect is limited.     

Propagation of phase-locked partially coherent flattened beam array in turbulent atmosphere

Analytical formulae for phase-locked partially coherent flattened beam array propagating in a turbulent atmosphere are derived based on the extended Huygens–Fresnel principle. Beam propagation factor (BPF) is introduced to evaluate the beam quality at the receiving plane. The influence of beam order, transverse coherence width length and the intensity of turbulence is discussed in detail.     

Thermodynamic properties of laburnine in saline and glucose solutions

Laburnine’s dissolution behaviors in glucose and saline solution were studied by a micro-calorimetry method. The measured integral and differential heats of solution were utilized to build equations of the solute and the heat, so that dissolution thermodynamic equations and half-time periods, Δ_sol H _m, Δ_sol G _m, and Δ_sol S _m were obtained. The results show that this study does not only provide a simple method for the determination of the half-life period for a drug but also offer a theoretical reference for the clinical application of laburnine.     

Influence of switchable magnetic field on the modulation property of nanostructured magnetic fluids

Magnetic fluid is a kind of colloidal material with tunable microstructure and unique optical properties. The tunable magneto-optical modulation property of magnetic fluid under externally switchable magnetic field with various modulation periods is investigated theoretically and experimentally. The transitional modulation period (lower limit of the working frequency) between the square-like and oscillation-like modulation is achieved and found to be magnetic-field- and sample-concentration-dependent. The modulation mechanism is analyzed and ascribed to the dynamic microstructure of magnetic fluid under different modulation periods of external magnetic fields. The result of this work may be helpful for the pragmatic applications of magnetic fluid based on the square-like modulation.     

Power scaling of blue and red light based on frequency mixing inside adhesive-free bond composite Nd:YAG laser cavity

We report our results on effective third-harmonic generation (THG) by cascading quasi-phase-matched second-harmonic and sum-frequency generation in a dual-period-periodically-poled KTP crystal. Significant improvement of the output powers were achieved for the 440 nm blue light and 660 nm red light based on Q-switched frequency-tripling and frequency-doubling 1319-nm radiation inside an adhesive-free bond composite Nd:YAG laser. The highest output powers of 197 mW and 1.19 W were achieved for the blue and red light at the corresponding input powers of 12.9 and 17.1 W for the diode laser.     

Coherent Beam Combination of Eight Watt-Level Polarization-Maintained Fiber Amplifiers

We demonstrate the coherent beam combination of eight Watt-level polarization-maintained fiber amplifiers. The phase control signal of each amplifier is generated by running a stochastic parallel gradient descent algorithm on a digital signal processor （DSP）. The experimental result shows that the whole system in close-loop performs well for long-time observation. Energy encircled in the target pinhole is 6.68 times more than that in open-loop. The combination efficiency is as high as 84.5%.