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3D hierarchical flower-like carbon coated MoO3−x nanosheets (denoted as MoO3−x NS@C) have been successfully fabricated by a simple hydrothermal method. When used as anode for Li-ion batteries, the MoO3−x NS@C electrode exhibits excellent cycle performance and outstanding rate capabilities. The charge capacity can reach 1025 mAh g−1 over 150 cycles, and 62% of the charge capacity is retained when the current density increases to 2000 mA g−1. The improved lithium storage performance of MoO3−x NS@C is attributed to the synergistic effect of oxygen vacancies and the carbon coating, which not only enhance the electric conductivity and Li-ion diffusion coefficient but also lead to superior structural stability and cyclability of the MoO3−x NS@C electrode during repeated lithiation/delithiation process.

The development of microsecond pulsed glow discharge atomic emission spectrometry (GD-AES) for quantitative depth profile analysis is described. The quantification method, which is based on sputtering rates, has been previously applied to depth analysis employing a dc glow discharge source. Optimal conditions of the glow discharge source, including voltage, pressure, pulse width and pulse frequency, are utilized in order to give the best depth resolution. Pulsed operation of the glow discharge affords the advantages of two additional parameters, pulse width and pulse frequency, which allow better control over the amount of sample being removed via cathodic sputtering. This allows thin layer samples to be analyzed that are very difficult using the dc source. Under the optimized parameters, thin coatings of varying depths of Cu deposited on steel were quantified. The quantitative method predicted Cu deposition depths in accord with the nominal depths.

A Grimm-type glow discharge ion source has been constructed for a time-of-flight mass spectrometer (TOF-MS). This source was operated in the microsecond-pulsed mode. Special features of pulsed Grimm GD-TOF-MS are described, including resolving power, stability, sensitivity and the temporal separation of discharge gas species and analyte ions. The analytical characteristics of a pulsed Grimm GD-TOF-MS system were also evaluated. These preliminary studies demonstrate the potential of this technique for the elemental analysis for solids.

A high voltage, microsecond regime, pulsed glow discharge has been applied to a standard Grimm type source on a LECO SA-2000 multichannel optical spectrometer. The spectrometer system has been equipped with fast time-resolved electronics in order to study the temporal response of the elemental emission lines. The aim of the research was to investigate possible gains in signal-to-background ratio (S/B) and detection limits compared to a conventional direct current (dc) mode of operation. It was found that the high instantaneous pulse power in itself gives approximately a factor 2 increase in S/B. By utilising time-resolved detection, gains in the range 5–10 are achieved. For nitrogen, it was found that the background from leakage of air could be reduced to approximately 1/3 compared with the dc mode. Another interesting observation was that certain nearly non-conducting materials, which cannot be run in dc mode, could be run in the microsecond pulsed mode.

Investigations have been performed using microsecond pulsed glow discharge atomic emission spectrometry (GD-AES) to determine the effect of the glow discharge parameters, including applied pulse voltage, pulse width, pulse frequency and gas pressure, on the resolution of depth profiling. The results indicate that a concave crater profile is obtained for low voltage, whereas the curvature is convex for high voltage. The criteria of a flat crater bottom and good depth resolution are fulfilled only with a limited range of voltages at each operating pressure. The results also imply that the pulse frequency and pulse width have little effect on the resolution of depth profiling; thus a wide dynamic range of layers from several nanometers to tens of micrometers can be analyzed by increasing or decreasing the pulse frequency and width. Under the optimized parameters, a thin coating of Cu (50 nm) on steel, an electroplated steel and a computer hard-disk with multiple thin layers were analyzed.

A high voltage, microsecond regime pulse dc glow discharge was applied to a standard Grimm source on a modified LECO SA-2000 direct reader spectrometer and to a duplicate Grimm source coupled to a scanning monochromator. The effects of experimental conditions, including pulse voltage, pulse frequency, pulse width and Ar pressure, on Cu atomic and ionic emission intensities were examined and compared with continuous discharge results. The pulsed Grimm source has a higher sputtering rate, greater signal intensity and lower detection limits. The pulsed signal for atomic lines shows a different temporal response from ionic lines. Pulsed Grimm GD-AES also offers control features advantageous in the measurement of thin surface layers.

A thermospray nebulizer was used as a sample introduction device for microwave plasma torch (MPT) atomic emission spectrometry (AES). Experimental parameters, including the power supplied to the MPT, the flow rates of support and carrier gases, the observation height, the sample uptake rate, the thermospray working temperature, the temperature of the aerosol spray chamber and cooling water were optimized. Under optimum conditions, the relative standard deviation (RSD) of 10 measurements for 21 elements is in the range 0.3–2.0%. The detection limits were improved in comparison with the ultrasonic nebulizer as sample introduction technique for MPT–AES. The inclusion of 20% methanol into the MPT showed there is no effect on the stability of MPT discharge. The technique can thus be held to have the potential for interface to reverse-phase HPLC systems.

A transient data acquisition system for flow injection analysis (FIA), high performance liquid chromatography (HPLC), and electrothermal vaporization (ETV) combined with ICP-AES multi-element instrumentation was developed and successfully applied to the analysis of different types of samples, including human serum, human hair and tea, for simultaneous multi-element determinations. The accuracy of the method was verified with hair reference material. Good agreement between the experimental results and certified values, and also satisfactory recoveries from standard additions, were achleved.

Palladium salts can be used as a coprecipitation carrier for the preconcentration of trace elements from natural water prior to their measurement by atomic spectrometry (AAS). The palladium is subsequently reduced by the introduction of hydrogen gas into the sample solution. The procedure is applied to the determination of Cu, Pb and Cd in seawater (enrichment factor 50) and synthetic water samples. Operating conditions have been optimized for the analysis of real samples. With the technique established an enrichment factor (500 fold) is feasible in synthetic samples. The recoveries of Cu, Cd and Pb from seawater are 95, 103 and 100%, respectively. This simple and rapid method can be applied in a wide pH-range and with complex matrices.

Over 100 hair samples were collected from the Xiamen area of south China, including 72 healthy people and 34 cancer patients, for the study of distinguishing cancer patients from others; another 64 hair samples were collected from patients with liver, stomach, lung, and miscellaneous cancers and were used for the discrimination analysis of different types of cancers, The samples were analyzed with ICP-AES for the simultaneous determination of several elements and with GFAAS for Se content after wet digestion. The average values of the element concentrations in the hair samples are presented. The results obtained were then analyzed with principal component analysis and partial least-squares methods, to distinguish cancer patients from others, and with an orthaganolization recurrence method to discriminate different types of cancers. The cancer patients could be completely distinguished from healthy people; while the misdiscrimination rates for the analysis of liver, stomach, and lung cancers are 15.8, 14.3, and 19.0%, respectively.

The determination of metal concentrations in fish with ICP-AES and FAAS was performed. Based on the metal concentrations found in fish collected from four regions of south China, principal component analysis was applied to a bioindicator study. The relationships between metal concentrations in fish tissues and those in seawater were studied by a simulated experiment. Using these relationships, the accumulation factors were determined, and the mean concentrations of Zn, Cd, Cu, and Pb in the coastal seawater of Min Jiang estuary, Dong Shan island, Me Zhuong island, and Hai Tan island were estimated.

The application of microsecond pulsed Grimm glow discharge atomic emission spectrometry for depth profiling of thin films is examined. The effects of pulsed conditions including pulse voltage, pulse frequency, pulse width, and Ar pressure on depth profiling performance were characterized for Zn and Cu coatings on steel. Using optimized conditions, linear calibration curves of coating thickness for Zn (6.1-26.9 μm) and Cu (50-500 nm) on steel were achieved. A precision of 2-5% relative standard deviation was determined. An ultrathin coating of Cu (10 nm) on steel was also measured by this technique.

The purpose of this paper is to discuss the physical properties of diffractionless beams, their propagation and transformation through optical systems. We start from the analysis of Durnin’s experiment to present a useful idea for the design of Bessel beam convertors. Then, the propagation of Bessel beams through ABCD optical systems are studied, and numerical calculations are performed to illustrate and compare the characteristics of truncated Bessel beams propagating through a sharp-edged aperture and a soft-edged one.

Based on the M 2 -factor concept and the equivalence between a beam generated by a gaussian Schell-model (GSM) source and a mixed-mode laser (MML) beam, a simple method is presented to estimate the number of effectively oscillating modes and the corresponding weighting factors of MML beams simultaneously.

Islanding detection is a significant technical barrier to the distributed generation (DG) industry. When islanding occurs, the inverter current of DG has a strong correlation with load voltage of DG. With respect to the correlation, this paper proposes an islanding detection method (IDM) based on periodic matching of the sequence perturbation. In this periodic code matching detection method, a periodic sequence is introduced to perturb the inverter current amplitude. The IDM can be achieved by calculating periodic matching degree between the islanding detection coefficient and the sequence. The influence on IDM imposed by sequence characteristics and load variation is also discussed in this paper. According to IEEE Std. 1547, an islanding detection model is designed and simulated in this paper. The simulation and experiment results indicate a strong ability to anti-harmonic noise when the 1-0 non-zeroing sequence with six bits is selected as the perturbation sequence. The proposed method introduces little damage to grid. In the normal range of voltage and frequency, this method can detect the islanding of DG reliably and effectively even if load varies.

A Grimm-type glow discharge ion source, operated in the microsecond pulsed mode, has been interfaced to a commercial time-of-flight mass spectrometer. Ion transport from the source to the mass spectrometer, an inherent limitation of a Grimm source and mass spectrometer combination, was evaluated. The primary discharge operating conditions found to influence transport efficiency were gas flow rate and source pressure. The configuration of the Grimm-type source also influenced ion transport, including use of a gas-directing sleeve device. The effect of transport efficiency was separated into two components: (1) total ion signal and (2) temporal resolution. The latter is an advantage afforded by use of a pulsed glow discharge source and time-of-flight spectrometer, which allows discrimination against interfering gaseous background ions by appropriate ion sampling time. Shown as an example is the identification of trace magnesium from potential background interference using an optimized source configuration based on this temporal resolution method.

A flexible and free-standing porous carbon nanofibers/selenium composite electrode (Se@PCNFs) is prepared by infiltrating Se into mesoporous carbon nanofibers (PCNFs). The porous carbon with optimized mesopores for accommodating Se can synergistically suppress the active material dissolution and provide mechanical stability needed for the film. The Se@PCNFs electrode exhibits exceptional electrochemical performance for both Li-ion and Na-ion storage. In the case of Li-ion storage, it delivers a reversible capacity of 516 mAh g−1 after 900 cycles without any capacity loss at 0.5 A g−1. Se@PCNFs still delivers a reversible capacity of 306 mAh g−1 at 4 A g−1. While being used in Na-Se batteries, the composite electrode maintains a reversible capacity of 520 mAh g−1 after 80 cycles at 0.05 A g−1 and a rate capability of 230 mAh g−1 at 1 A g−1. The high capacity, good cyclability, and rate capability are attributed to synergistic effects of the uniform distribution of Se in PCNFs and the 3D interconnected PCNFs framework, which could alleviate the shuttle reaction of polyselenides intermediates during cycling and maintain the perfect electrical conductivity throughout the electrode. By rational and delicate design, this type of self-supported electrodes may hold great promise for the development of Li-Se and Na-Se batteries with high power and energy densities.

In this paper, a thin-disk laser with the output power of kW level is demonstrated. The laser used is Nd:YAG laser medium for easiness to reach the threshold power densities of the pump and less heat to dissipate from the crystal. The thin disk of 1 mm thickness with 1.5-at. % Nd doped and a simple 4-pass pump coupling system is designed to fulfill the total absorption of the pump light. 2D-stacks diode array works as the pump source and a conventional optics is used for efficient and uniform pumping.

A diode-laser side-pumped E-O Q-switched TEM00 Nd:YAG slab laser that uses a large N.A. cylindrical lens and a thin slab pumping geometry has been investigated. The pumping scheme has the ability to match well the pump beam to the laser's fundamental transverse mode in two axes. Approximately 1.1 times diffraction limited laser beam is obtained. The slope efficiency is 31% and 18.9% at long-pump and Q-switched operation, respectively.© (1998) COPYRIGHT SPIE--The International Society for Optical Engineering. Downloading of the abstract is permitted for personal use only.

The diode laser side pumped E-O Q-switch Nd:YAG laser was described that produced energy O.36-mJ/pulse. 7-nspulse width ,pulse repetition rates 50-Hz, TEM00 mode.The laser has a zigzag slab geometry, side pumped with a quasi- cw 15Wdiode bar. We used a 1 .1%Nd:YAG Brewster-cut seven-bounce thin trapezoidal slab that was 1 .2mm thick.Using a cylindrical lens (f=1 .6nim),it made the diode laser couple in the slab. The laser resonator was a plane-concavecavity, radius of mirror curvature was 3m. The cavity length was about 20cm. The plane output mirror transitivity was T=0. 1 . Wedecided to the beam quality M2=1 . 1 . Q-switchlaser slope efficiency was 19%. keyword solid-state lasers, side pumped, diode laser, single transverse mode 1 .INTRODUCTION Diode-laser(LD) pumped solid-state lasers have been one ofthe most interesting and significant developments in laserengineering in recent years1. LD pumping offered high reliability, efficiency and compactness. Side pumping has been togenerate the fundamental transverse mode efficiently2. Recently a side pumping technique used in Q-switch cavity-dumpedand E-O Q-switch laser3 demonstrated efficiency side-pumped operation while still maintaining TEM00 operation. Wereported on a E-O Q-switched laser that used a numerical aperture(NA>1) and short focus length (f=1 .6mm) cylindricallens coupler thin Nd:YAG thin trapezoidal slab and generated 0.36-mJ, 7-ns, TEMo0. pulse repetition rates 50Hz whileusing

Pulsing the glow discharge offers new experiments and applications with a well-established technique.