Development of a portable analyzer using solid-phase microextraction coupled with thermal desorption digitally-controlled plasma optical emission spectrometry for the determination of mercury volatile compounds released from sediments

Novel multi-species analyzer based on thermal desorption and digitally-controlled plasma optical emission spectrometry followed by solid-phase microextraction has been developed for determining various organometallics in sediment samples. A helium plasma source operating at 10?kHz and an integrated small-sized spectrometer with a charge-coupled device detector is installed for cost-effective atomic emission measurement and signal acquisition. Moreover, the analyzer size of a portable device is achieved, while the system is capable of absorbing large amounts of measurement data. Specifically, the analyzer has been applied for the speciation of mercury species in sediments. Method detection limits for MeHg and Hg²⁺ are 35.4 and 9.6?ng L^?1. Thus, sediments containing above 0.2 µg kg^?1 of mercury can be analyzed with precision 1–3.5% of RSD. The developed methods are validated by the analysis of estuarine sediment certified reference material ERM CC580, GBW 07405 Chinese soil. [AQ1]     

Shaking table experimental study on the effectiveness of polymer bearings for seismic isolation of structures

Seismic isolation has been recognised to be a very effective way of protecting structures from damage during earthquakes. It allows us to extend the natural period of the structure and therefore avoid resonance with the ground motion. Moreover, by increasing damping in the isolation devices, more energy can be dissipated and thus the structural response can be further reduced. The aim of this paper is to show the results of the study focused on verification of the applicability of the innovative method of seismic isolation by installing bearings made of a polymer mass, which is an especially designed flexible elastoplastic two-component grout based on polyurethane resin. In the study, a model structure was tested experimentally on a shaking table under earthquake excitation. First, the structure was fixed directly to the table and its response was recorded. Then, the response of the structure with polymer bearings installed at its base was observed and both responses were compared. The results of the study show that equipping the structure with the polymer bearings can considerably reduce the structural response under earthquake excitation. The innovative method considered in the study has been verified to be an effective seismic isolation technique. (© 2009 Wiley-VCH Verlag GmbH & Co. KGaA, Weinheim)     

Polyethyleneimine coating renders polycarbonate resistant to organic solvents

We propose a method for the modification of surfaces of microchannels in chips fabricated in polycarbonate (PC) that makes the devices resistant to a range of organic solvents. Coating of PC with branched polyethyleneimine (BPEI) with the use of trimethylpropane triglycidyl ether (TTE) as a linker renders the devices resistant to toluene, benzene, acetonitrile, tetrahydrofuran, dioxane and ethylene dichloride. The optimized procedure of modification allows for continuous operation of the chips for several hours without dissolution of PC. Additional modification with the use of Krytox? allows for the use of Fluorinert (FC-40) as the continuous phase and for generation and handling of droplets of organic solvents that are miscible with water.     

An investigation of the reliability of the Galerkin-Petrov method with a special study of the helium atom ground state

A convergence characterization of the Galerkin-Petrov method by means of quantities characterizing pairs of subspaces is presented. The usefulness of our approach for setting up reliable computational schemes is demonstrated for the He atom ground state. Several methods of constructing pairs of subspaces for use in quantum chemistry are suggested.     

Approximate generation of full-dimensional ab initio van der Waals surfaces for high-resolution spectroscopy

A method for the generation of highly accurate, nearly-exact, full-dimensional interaction energy surfaces for weakly interacting subsystems is proposed. The method is based on the local expansion of the exact interaction energy surface in the Taylor series with respect to intramolecular coordinates. It is shown that without any significant loss of accuracy this expansion can be limited to a few low-order terms. This leads to significant savings in computations of the full-dimensional interaction energy surfaces. Also a method for the direct calculation of the interaction energy surface of reduced dimensionality, corresponding to averaging over the intramolecular vibrations, without explicit knowledge of the full-dimensional surface, is presented. The main ideas and computational features of the proposed scheme are comprehensively tested for the Ar-HF system.     

Synthesis, proton and 13C NMR and reaction mechanism studies of novel isoindolones derivatives, obtained through TAWERS procedure

A series of novel isoindolone derivatives (13-18) were prepared in goods yields by applying the TAWERS methodology. A general approach for formation of isoindolones from the aza-Wittig reaction of iminophosphoranes with dialdehydes under neutral and mild conditions was realized. Using 1D NMR a [1,3]-hydride migration was detected. The assignment of the structures and conformation behavior of the derivatives was achieved using 1D and 2D NMR (NOESY, DEPT, HMQC, and HMBC).     

2D H and C NMR conformational studies of thienopyridines and carboline biarylic compounds

In this paper, we report on conformational studies of biarylic compounds, as prepared through the well-known aza-Wittig methodology. The conformational studies were mainly realized by bidimensional (2D) nuclear magnetic resonance spectroscopy (NMR) and NOESY experiments. The conformational behavior showed that these biarylic compounds display an orthogonal symmetry and adopt a characteristic arrangement around the pivotal bond. Molecular modeling calculations were performed to support structure conformations.     

Stereochemistry of 1-hydroxyphosphonate-phosphate rearrangement. Retention of configuration at the phosphorus atom

1-Hydroxyphosphonate 1 in the presence of triethylamine in acetonitrile solution undergoes irreversible rearrangement to phosphate 2 and reversible retro-phospho-aldol (retro-Abramov) reaction. The X-ray structures for 1 and 2 revealed that the phosphonate-phosphate rearrangement occurs with retention of configuration at the phosphorus atom.     

Numerical-Analytic Methods for Differential-Algebraic Systems

The numerical-analytic method is useful to show that a differential equation with a boundary condition has a solution. In this paper we use this method to differential-algebraic systems with boundary conditions. Some existence results are formulated under assumptions that the corresponding functions satisfy Lipschitz conditions in matrix notation.