The evolution of comprehensive two-dimensional gas chromatography (GC x GC)

For a technology little over a decade old, comprehensive two-dimensional gas chromatography (GC x GC) has quickly reached the status of one of the most powerful analytical tools for volatile organic compounds. At the heart of any GC x GC system is an interface, which physically connects the primary and the secondary columns and acts to preserve the separation obtained in the first dimension (first column) while allowing additional separation in the second dimension. The paper presents a review of the technology, including fundamental principles of the technique, data processing and interpretation and a timeline of inventive contributions to interface design. In addition, applications of the technique are presented, with a more detailed discussion of selected examples.     

Spatial dependency of the groundwater uranium in the alluvial soil region of Gunnaur,India

Journal of Radioanalytical and Nuclear Chemistry - GIS based groundwater uranium and other physico-chemical parameters pH, electrical conductivity, oxidation reduction potential, temperature,...     

Galerkin method for a Stefan-type problem in one space dimension

Based on a Landau-type transformation, both continuous and discrete in time L²-Galerkin methods are applied to a single-phase Stefan-type problem in one space dimension. Optimal rates of convergence in L^ℵ, L^∞, and H¹-norms are derived and computational results are presented. © 1997 John Wiley & Sons, Inc. Numer Methods Partial Differential Eq 13: 393–416, 1997     

Semidiscrete finite element Galerkin approximations to the equations of motion arising in the Oldroyd model

In this paper, a semidiscrete finite element Galerkin methodfor the equations of motion arising in the 2D Oldroyd modelof viscoelastic fluids with zero forcing function is analysed.Some new a priori bounds for the exact solutions are derivedunder realistically assumed conditions on the data. Moreover,the long-time behaviour of the solution is established. By introducinga Stokes–Volterra projection, optimal error bounds forthe velocity in the L(L²) as well as in the L(H¹)-norms andfor the pressure in the L(L²)-norm are derived which are validuniformly in time t > 0.     

A second-order splitting combined with orthogonal cubic spline collocation method for the Rosenau equation

A second-order splitting method is applied to a KdV-like Rosenau equation in one space variable. Then an orthogonal cubic spline collocation procedure is employed to approximate the resulting system. This semidiscrete method yields a system of differential algebraic equations (DAEs) of index 1. Error estimates in L² and L^∞ norms have been obtained for the semidiscrete approximations. For the temporal discretization, the time integrator RADAU5 is used for the resulting system. Some numerical experiments have been conducted to validate the theoretical results and to confirm the qualitative behaviors of the Rosenau equation. Finally, orthogonal cubic spline collocation method is directly applied to BBM (Benjamin–Bona–Mahony) and BBMB (Benjamin–Bona–Mahony–Burgers) equations and the well-known decay estimates are demonstrated for the computed solution. © 1998 John Wiley & Sons, Inc. Numer Methods Partial Differential Eq 14: 695–716, 1998     

On the structure of 3‐acetylamino‐5‐methyl‐1,2,4‐oxadiazole and on the fully degenerate rearrangements (FDR) of its anion: a stimulating comparison between the results of ‘in‐silicon chemistry’ and ‘laboratory chemistry’

An accurate crystal structure determination has provided evidence for a planar conformation for 3‐acetylamino‐5‐methyl‐1,2,4‐oxadiazole ( 5 ), in agreement with quantum‐mechanical calculations in the gas phase. In the crystal, a series of strong intermolecular N7H7^….O9 hydrogen bonds link the amido groups of different molecules, causing the formation of infinite parallel ordered chains. The effect of the DMSO solvent on the energy and charge distribution of compound 5 and on its relevant 5 ^? anion, involved in a fully degenerate rearrangement (FDR), has been deepened by quantum‐mechanical DFT calculations. The calculated energy barrier for the FDR increases in going from in vacuo to DMSO, in agreement with previsions based on the Hughes and Ingold rules concerning the nucleophilic substitution of an anionic reagent (the deprotonated amido group in the side chain) on a neutral substrate (the 1,2,4‐oxadiazole ring). Copyright © 2009 John Wiley & Sons, Ltd.     

Asymptotic behavior and finite element error estimates of Kelvin-Voigt viscoelastic fluid flow model

In this article, the convergence of the solution of the Kelvin-Voigt viscoelastic fluid flow model to its steady state solution with exponential rate is established under the uniqueness assumption. Then, a semidiscrete Galerkin method for spatial direction keeping time variable continuous is considered and asymptotic behavior of the semidiscrete solution is derived. Moreover, optimal error estimates are achieved for large time using steady state error estimates. Based on linearized backward Euler method, asymptotic behavior for the fully discrete solution is studied and optimal error estimates are derived for large time. All the results are even valid for κ→0, that is, when the Kelvin-Voigt model converges to the Navier-Stokes system. Finally, some numerical experiments are conducted to confirm our theoretical findings.     

7‐Chloro‐3,6‐di­methyl‐1H‐indene‐2‐carb­aldehyde

In the crystal structure of C₁₂H₁₁ClO, the (planar) mol­ecules give rise to a parallel packing. A model crystal obtained by semi‐empirical and packing‐energy calculations is consistent with the observed structure.     

Electrocatalytic activity of sol-gel-prepared RuO2/Ti anode in chlorine and oxygen evolution reactions

Electrocatalytic properties of RuO₂/Ti anode with different coating masses, which are prepared by the alkoxide sol-gel procedure, are investigated in chlorine and oxygen evolution reactions by polarization measurements and electrochemical impedance spectroscopy in H₂SO₄ and NaCl electrolytes. According to polarization measurements, the activity of anodes at overpotentials below 100 mV is independent of coating mass. However, impedance measurements above 100 mV reveal changes in the activity of anodes in chlorine evolution reaction for different coating masses. The diffusion limitations related to the evolved chlorine are registered in low-frequency domain at 1.10 V (SCE), diminishing with the increase in potential to the 1.15 V (SCE). The observed impedance behavior is discussed with respect to the activity model for activated titanium anodes in chlorine evolution reaction involving formation of gas channels within porous coating structure. Gas channels enhance the mass transfer rate similarly to the forced convection, which also increases the activity of anode. This is more pronounced for the anode of greater coating mass due to its more compact surface structure. The more compact structure appears to be beneficial for gas channels formation. Published in Russian in Elektrokhimiya, 2006, Vol. 42, No. 10, pp. 1173–1179. The text was submitted by the authors in English.