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Reactions of Acetyl Radical with Acetylene - A Computational Study

  • Tran, Tu Anh;Schiesser, Carl H.
    • Bulletin of the Korean Chemical Society
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    • v.31 no.3
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    • pp.595-598
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    • 2010
  • Ab initio and DFT molecular orbital calculations predict that acetyl radical reacts with acetylene through interactions primarily involving the SOMO of the radical and the in-plane ${\pi}$-bond of acetylene. An energy barrier (${\Delta}E_1$) of 39.6 kJ $mol^{-1}$ is predicted for the preferred anti arrangement of reactants at the CCSD(T)/cc-pVDZ//BHandHLYP/cc-pVDZ level of theory. NBO analysis reveals additional interactions between the radical SOMO and the nearby C-H ${\sigma}$-bond in acetylene worth about 10% of the total transition state interaction energy. This type of orbital interaction has not previously been observed in radical addition reactions involving C-C ${\pi}$-bonds.

Processing parallel-disk viscometry data in the presence of wall slip

  • Leong, Yee-Kwong;Campbell, Graeme R.;Yeow, Y. Leong;Withers, John W.
    • Korea-Australia Rheology Journal
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    • v.20 no.2
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    • pp.51-58
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    • 2008
  • This paper describes a two-step Tikhonov regularization procedure for converting the steady shear data generated by parallel-disk viscometers, in the presence of wall slip, into a shear stress-shear rate function and a wall shear stress-slip velocity functions. If the material under test has a yield stress or a critical wall shear stress below which no slip is observed the method will also provide an estimate of these stresses. Amplification of measurement noise is kept under control by the introduction of two separate regularization parameters and Generalized Cross Validation is used to guide the selection of these parameters. The performance of this procedure is demonstrated by applying it to the parallel disk data of an oil-in-water emulsion, of a foam and of a mayonnaise.

Splice Site Detection Using a Combination of Markov Model and Neural Network

  • M Abdul Baten, A.K.;Halgamuge, Saman K.;Wickramarachchi, Nalin;Rajapakse, Jagath C.
    • Proceedings of the Korean Society for Bioinformatics Conference
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    • 2005.09a
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    • pp.167-172
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    • 2005
  • This paper introduces a method which improves the performance of the identification of splice sites in the genomic DNA sequence of eukaryotes. This method combines a low order Markov model in series with a neural network for the predictions of splice sites. The lower order Markov model incorporates the biological knowledge surrounding the splice sites as probabilistic parameters. The Neural network takes the Markov encoded parameters as the inputs and produces the prediction. Two types of neural networks are used for the comparison. This method reduces the computational complexity and shows encouraging accuracy in the predictions of splice sites when applied to several standard splice site dataset.

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Simulations of pendant drop formation of a viscoelastic liquid

  • Davidson Malcolm R.;Harvie Dalton J.E.;Cooper-White Justin J.
    • Korea-Australia Rheology Journal
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    • v.18 no.2
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    • pp.41-49
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    • 2006
  • A modified Volume-of-Fluid (VOF) numerical method is used to predict the dynamics of a liquid drop of a low viscosity dilute polymer solution, forming in air from a circular nozzle. Viscoelastic effects are rep-resented using an Oldroyd-B model. Predicted drop shapes are compared with experimental observations. The main features, including the timing of the shape evolution and the 'bead-on-a-string' effect, are well reproduced by the simulations. The results confirm published conclusions of the third author, that the deformation is effectively Newtonian until near the time of Newtonian pinch-off and that the elastic stress becomes large in the pinch region due to the higher extensional flow there.