An MSFIA system for mercury speciation based on an anion-exchange membrane

A new methodology for the in-line preconcentration, clean-up and speciation of mercury by use of an anion-exchange membrane is proposed. The speciation of mercury is based on retention of its tetrachloro complex onto the membrane while organic mercury flows freely through it. A multisyringe is used as a liquid driver and a cold vapour atomic fluorescence detector is employed to ensure a high sensitivity. Organic mercury is decomposed into to inorganic mercury by using a UV lamp. The carrier and reductant streams consist of 1.5% (m/v) hydrochloric acid and 2% (m/v) tin chloride, respectively. Certified reference material DORM-2 was digested with 37% hydrochloric acid and analysed directly without the need for extraction. The proposed system is more environmental friendly than the classical liquid-liquid extraction procedure. Mercury recoveries from spiked samples and the reference material were all close to 100%. An LOD of 14 and 16 ng/L was obtained for total and organic mercury, respectively, both with an RSD less than 1.3%.     

Squeezing and sub-Poissonian effects up-to fourth order in fifth harmonic generation

The concept of squeezing of the electromagnetic field is investigated in fundamental mode in fifth harmonic generation with the approximation |gt|²?1, where g is coupling constant and t, the interaction time between waves during the process. It has been found that squeezing occurs in amplitude, amplitude-squared, amplitude-cubed and fourth-order amplitude states of the field for selective phase values of field amplitude of fundamental mode. The dependence of squeezing on the photon number has also been investigated and found to be sub-Poissonian in nature. The signal to noise ratio has been studied in different order. It is found that the signal to noise ratio is higher in lower order.     

An X‐shaped π‐conjugated polymer comprising of fluorene units and anthracene units with high efficiency. Synthesis and optical and electrochemical properties

A new X‐shaped π‐conjugated monomer comprising of fluorene units and anthracene units was synthesized, and it was used to fabricate the new X‐shaped π‐conjugated polymers and investigate the properties of the new polymers. Using different molar ratios between such monomer and a fluorene monomer gave three polymers that showed higher absolute PL quantum yields than the linear polyfluorene (PF) in the solid state. After thermal annealing at 200 °C for 4 h, the linear PF showed an additional bathochromic emission at about 550 nm, whereas such red‐shifted emission was fully eliminated for the X‐shaped polymers. The electroluminescent devices based on the X‐shaped polymers with a configuration of ITO/PEDOT:PSS/polymer/LiF/Ca/Al displayed blue emission with low turn‐on voltage and high brightness. © 2008 Wiley Periodicals, Inc. J Polym Sci Part A: Polym Chem 46: 5616–5625, 2008     

Spectroscopic determination of binding between human serum albumin and a platinum(II) dimethylsulfoxide complex

We have used electronic absorption and fluorescence spectroscopy to study binding between a platinum(II) dimethylsulfoxide complex (cis-[Pt(DMSO)₂Cl₂]) and human serum albumin (HSA), and the effect of complexation on the structure of the protein. We have calculated the binding parameters for binding between cis-[Pt(DMSO)₂Cl₂] and HSA. We have determined the binding constant K_B = (1.2 ± 0.1)·10³ M⁻¹ and the Hill coefficient h = 1.03 ± 0.1. We have determined that binding between cis-[Pt(DMSO)₂Cl₂] and the protein leads to a change in the internal packing of the macromolecule. __________ Translated from Zhurnal Prikladnoi Spektroskopii, Vol. 75, No. 4, pp. 573–576, July–August, 2008.     

Conjugated polymers containing electron‐transporting,hole‐transporting,and light‐emitting units in the polymer main chain

Conjugated polymers containing electron‐transporting, hole‐transporting, and blue light‐emitting units were synthesized by Suzuki polycondensation. These copolymers exhibited excellent thermal and optical stability. Optical investigation indicated that the incorporation of the spirobifluorene units in the polymer main chain could markedly increase the effective conjugation length of polymers. Electrochemical studies showed that the incorporation of spirobifluorene unit could raise the electrochemical stability and improve the electron‐ and hole‐injecting abilities. The electroluminescent results also showed that the introducing of spirobifluorene units could significantly improve the device performance. © 2008 Wiley Periodicals, Inc. J Polym Sci Part A: Polym Chem 46: 1349–1356, 2008     

New 1,3,5-triphenyl-2-pyrazoline-containing 3-hydroxychromones as highly solvatofluorochromic ratiometric polarity probes

Two novel 1,3,5-triphenyl-2-pyrazoline moiety containing derivatives of 3-hydroxychromone were synthesized and studied by ¹H NMR, absorption and fluorescence spectroscopy. The prospects of practical application of these compounds exhibiting high solvatofluorochromism into analytical chemistry and biophysics as effective ratiometric polarity probes were discussed proceeding from the data on their fluorescent properties.     

Two novel methods for vibration diagnosis to characterize non-linear response

Poincaré maps have been proved to be a valuable tool in the analysis of non-linear dynamical systems, which usually reduce a continuous phase flow into a two-dimensional discrete map. However, they may be inconvenient for reflecting some characteristics of the system response. In this paper, two novel methods, using the period sampling peak-to-peak value (PSP) diagram and the modified Poincaré map, are presented for characterizing different types of non-linear response. These two methods take advantage of some parameters of the response, such as the peak-to-peak value within an exterior excitation period and the mean value of the displacement. In the PSP diagram method, a two-dimensional graph is plotted by taking the peak-to-peak value as ordinate and the sequential periodically sampling number as abscissa. On the other hand, the modified Poincaré map takes the mean value of the velocity within an exterior excitation period as ordinate and the relevant mean value of the displacement as abscissa. The non-linear responses of a Duffing system, a pendulum with circular motion support and an oscillating circuit are studied by these methods. We also studied the intermittent chaos of the Lorenz system by the PSP diagram method. The PSP diagram is a set of mapping points, which form: a straight line for a one-period response; multi-straight lines for a multi-period response; orderly periodic curves for a quasi-period response; long lines interrupted by transitoriness confusion points for intermittent chaos; and totally out-of-order points for chaos. The figures for the modified Poincaré maps for the period, multi-period, quasi-period responses and chaos are almost identical to those for the Poincaré maps, but the modified maps take more sampling points and can reflect the mean values of the responses. Some numerical results are given based on these methods to show their efficiency in distinguishing different non-linear responses.     

Spectral Decomposition of Intracellular Complex Fluorescent Signals Using Multiwavelength Phase Modulation Lifetime Determination

Lifetime-based spectral decomposition using a frequency-domain phase/modulation technique has been developed on our UV confocal microspectrofluorimeter prototype. Examples of such an application are first given in the case of complex mixtures of three overlapping fluorescent components in solution. Preliminary results concerning cellular potential application are also reported in the case of Snarf-1 pH sensor. Limits and perspectives of such an approach at the subcellular level are discussed in view of future improvement.