Simultaneous spectrophotometric determination of zinc, cadmium and mercury with hybrid linear analysis

A new method for simultaneous spectrophotometric determination of Zn, Cd and Hg using 2-(5-Br-2-pyridylazo)-5-diethylaminophenol as the color developing reagent was proposed. The absorption spectra of these three complexes have similar features with severe overlap in visible spectral range. For resolving these spectra, hybrid linear analysis was used, and the pure spectrum of each component was obtained from the calibration mixtures by least squares method. The effects of reaction condition, selection of wavelengths, determination of pure spectrum and additivity of absorbances etc. on the determination were discussed. The proposed method offers the advantages of simple, rapid, and accuracy. It has been successfully applied to the simultaneous determination of Zn, Cd and Hg in synthetic sample. A comparison was also made with the partial least squares method.

Simultaneous Laser-Induced Fluorescence And Contactless-Conductivity Detection For Microfluidic Chip

A combined detection system involving simultaneous LIF and contactless-conductometric measurements at the same place of the microfluidic chip was described. The LIF measurement was designed according to the confocal principle and a moveable contactless-conductivity detector was used in (CD)-D-4. Both measurements were mutually independent and advantageous in analyses of mixtures. Various experimental parameters affecting the response were examined and optimized. The performances were demonstrated by simultaneous detection of Rhodamine B. And the results showed that the combined detection system could be used sensitively and reliably. (C) 2008 Yong Yu. Published by Elsevier B.V. on behalf of Chinese Chemical Society. All rights reserved.

Materials selection in mechanical design for microsensors and microactuators

Microsensors and microactuators are vital organs of microelectromechanical systems (MEMS), forming the interfaces between controller and environment. They are usually used for devices ranging in size at sub-millimeter or micrometer level, transforming energy between two or more domains. Presently, most of the materials used in MEMS devices belong to the silicon material system, which is the basis of the integrated circuit industry. However, new techniques are being explored and developed, and the opportunities for MEMS materials selection are getting broader. The present paper tries to apply 'performance index' to select the material best suited to a given application, in the early stage of MEMS design. The selection is based on matching performance characteristics to the requirements. A series of performance indices are given to allow a wide range comparison of materials for several typical sensing and actuating structures, and a rapid identification of candidates for a given task. (C) 2002 Elsevier Science Ltd. All rights reserved.

Effect of surface tension on the mode selection of vertically excited surface waves in a circular cylindrical vessel

Singular perturbation theory of two-time-scale expansions was developed in inviscid fluids to investigate patternforming, structure of the single surface standing wave, and its evolution with time in a circular cylindrical vessel subject to a vertical oscillation. A nonlinear slowly varying complex amplitude equation, which involves a cubic nonlinear term, an external excitation and the influence of surface tension, was derived from the potential flow equation. Surface tension was introduced by the boundary condition of the free surface in an ideal and incompressible fluid. The results show that when forced frequency is low, the effect of surface tension on the mode selection of surface waves is not important. However, when the forced frequency is high, the surface tension cannot be neglected. This manifests that the function of surface tension is to cause the free surface to return to its equilibrium configuration. In addition, the effect of surface tension seems to make the theoretical results much closer to experimental results.

Water and salt movements in simultaneous flood-irrigation and well-drainage operations

This paper describes a new technology for solonchak soil reclamation in which surface flood irrigation of fresh water and pumped wells drainage of salty groundwater are combined. The comprehensive investigation of water and salt movement has been conducted through field test, laboratory simulation and numerical calculation. The dependence of desalination on irrigation water quantity, drainage quantity, leaching time and other parameters is obtained based on the field tests. The entire desalination process under the flood-irrigation and well-drainage operations was experimentally simulated in a vertical soil column. The water and salt movement has been numerically analysed for both the field and laboratory conditions. The present work indicates that this new technology can greatly improve the effects of desalination.

The mechanism of pattern selection in coupled map lattices

The pattern selection of one-dimensional coupled map lattices is studied in this paper. It is shown by spatiotemporal variable separation that there exists a threshold wavelength in pattern selection which possesses wave-like structures in space and periodic chaotic motion in time.

Simultaneous measurement of temperature, density and velocity in gas-flows by modulated photoluminescence

A novel possibility to determine the temperature, density and velocity simultaneously in gas flows by measuring the average value, amplitude of modulation and phase shift of the photoluminescence excited by a temporally or spatially modulated light source is investigated. Time-dependent equations taking the flow, diffusion, excitation and decay into account are solved analytically. Different experimental arrangements are proposed. Measurements of velocity with two components, and temporal and spatial resolutions in the measurements are investigated. Numerical examples are given for N z with biacetyl as the seed gas. Practical considerations for the measurements and the relation between this method and some existing methods of lifetime measurement are discussed.

COLOR-HOLOGRAPHY USING THE ANGULAR SELECTIVITY OF VOLUME RECORDING MEDIA

A display hologram of an object can be recorded and reconstructed in three primary colors if the angular selectivity of volume recording media is exploited. Three holograms are recorded in the same medium, each at a different primary color. These three holograms are reconstructed by simultaneous illumination of the hologram with the original reference beams. By proper choice of the angles that the reference beams make to the hologram, it is possible to suppress strongly cross talk between the different reconstructions (e.g., the red object reconstruction in green light). The technique exhibits high resolution, high diffraction efficiency, and vivid colors. Through the addition of three holographically recorded volume gratings it is possible to reconstruct the hologram with a beam of white light. The saturation and brightness of each primary color in the reconstruction can be adjusted by selection of an appropriate thickness for the corresponding grating.

Simultaneous three-photon absorption induced ultraviolet upconversion in Pr3+:Y2SiO5 crystal by femtosecond laser irradiation

Near-infrared to ultraviolet upconversion luminescence was observed in the Pr3+ :Y2SiO5 crystal with 120 fs, 800 mn infrared laser irradiation. The observed emissions at around 270 nm and 305 nm could be assigned to 5d -> 4f transitions of Pr3+ ions. The relationship between the upconversion luminescence intensity and the pump power of the femtosecond laser reveals that the UV emission belongs to simultaneous three-photon absorption induced upconversion luminescence. (c) 2007 Elsevier B.V. All rights reserved.

Simultaneous phase-shifting ellipsometry based on grating beamsplitter

Simultaneous phase-shifting ellipsometry based on a grating beamsplitter is presented. In the corresponding setup, an orthogonal grating and analyzer array are used. The latter is composed of four separate analyzers arranged in a 2x2 grid, the polarization axes of which are set to 0, 45, 90, and 135 deg. A mask allows only four diffracted beams of the fist order, having the same optical intensities, to pass. Each beam is incident on one of the analyzers of the array. The intensities of the four beams are simultaneously detected by a quadrant detector. The ellipsometric parameters are obtained using the four intensity signals. The feasibility of simultaneous phase shifting ellipsometry is thus demonstrated. (C) 2008 Society of Photo-Optical Instrumentation Engineers.

Simultaneous three-photon-excited violet upconversion luminescence of Ce3+: Lu2Si2O7 single crystals by femtosecond laser irradiation

We found that Ce3+:Lu2Si2O7 single crystals could be excited at 800 nm by using a femtosecond Ti:sapphire laser. The emission spectra of Ce3+:Lu2Si2O7 crystals were the same for one-photon excitation at 267 nm as for excitation at 800 nm. The emission intensity of Ce3+: Lu2Si2O7 crystals was found to depend on the cube of the laser power at 800 nm, consistent with simultaneous absorption of three 800 nm photons. The measured value of the three-photon absorption cross section is sigma'(3) = 2.44 x 10(-77) cm(6) s(2). (c) 2006 Optical Society of America.