• Analytical Science and Technology
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• v.6 no.4
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• pp.383-390
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• 1993

Retention behaviors of aliphatic and aromatic compounds were investigated with Van der Waals volume which represented the molecular size. The organic solvents, methanol, acetonitrile and tetrahydrofuran, were mixed with water at various ratio, respectively. The selectivity of organic solvents were tested by change of column temperature. The capacity factor was increased linearly according to the enlargement of molecular size. Therefore, Van der Waals volume was useful to predict the elution of organic molecules in reversed-phase column. The order of elution capacity of solvents was methanol

• Journal of the Korean Chemical Society
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• v.46 no.6
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• pp.545-549
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• 2002

Many theories for polymeric liquids are based on the concepts of cell, hole, free volume or lattice etc. In the theories, van der Waals potential, Lennard-Jones 6-12 potential and their modified potentials are commonly used.In this work, Mie(p, 6) potential was applied to the Continuous Lattice Fluid Theory (which extends the discrete lattices of Lattice Fluid Theory to classically continuous lattices) and Dee-Walsch's Cell Theory (which modifies Flory's Equa-tion of State Theory). Both of them are known to be successful theories for polymeric liquids. Thus, PVT values chang-ing with p (the exponent in the repulsion potential) were calculated and compared with experimental values. And, calculated values of Lattice Fluid Theory, Flory's Equation of State Theory and Cho-Sanchez Theory using pertubation method were also compared. Through the calculated results, van der Waals potential, Lennard-Jones 6-12 potential and Mie(p, 6) potential for polymeric liquids were compared with each other.

• Journal of the Korean Chemical Society
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• v.44 no.6
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• pp.587-591
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• 2000

Many theories have been suggested to obtain an equation of state for polymeric liquids. Most of them are based on the concepts of cell, hole, free volume or lattice etc. One of the most succesful theories is an equation of state theory of Flory and his coworkers based on the concept of free volume. In this work, van der Waals potential used in Flory's theory was modified, giving a new equation of state for polymeric liquids. The calculated results showed that the new equation of state gave better agreement with experimental PVT data than Flory's theory.

• YAKHAK HOEJI
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• v.53 no.5
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• pp.281-285
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• 2009

The retention of solutes in reversed-phase high-performance liquid chromatography depends on their hydrophobicity. Although the retention behaviors of alkyl benzenes have been reported so far, quite a few authors have mentioned the retention behavior of alkyl benzenes with plural hydrophobicity parameters. In this sense, we were interested in the retention behaviors of alkyl benzenes having benzene moiety and increasing alkyl chain. In this study, we therefore investigated the retention behavior of alkyl benzenes in reversed-phase high-performance liquid chromatography in order to obtain information concerning the effects of the aromatic moiety and the carbon chain on the retention mechanism by comparing their capacity factor (k') in relation to the carbon chain length. The eluent acetonitrile ($CH_3CN$) showed high selectivity on alkyl benzenes, showing the high difference of capacity factor (${\Delta}log\;k'$) between toluene and octyl benzene. Indeed, the ${\Delta}log\;k'$ of 80% $CH_3CN$ represented 1.42- and 4.25-times longer than 90% MeOH and 60% THF, respectively. The hydrophobicity parameters, van der Waals volume, bond constant, partition constant, $\pi$-energy effect and enthalpy were evaluated with the capacity factor (k') of alkyl benzenes eluted on 80% CH3CN, 90% MeOH and 60% THF, respectively. The best eluent for predicting retention behavior of alkyl benzenes was 90% MeOH ($R^2$ 0.999). The three parameters, van der Waals volume, bond constant and partition constant were well coincident to log k' by increasing alkyl benzenes. However, $\pi$-energy effect and enthalpy were severely disagreeable. Taken together, van der Waals volume, bond constant and partition constant were a reliable parameters to predict the retention behaviors of alkyl benzenes on reversed-phase column.

• The KIPS Transactions:PartA
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• v.19A no.4
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• pp.169-174
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• 2012

We present an algorithm that computes a 3 dimensional Voronoi diagram for a protein molecule in this paper. The molecule is represented as a set of spheres with van der Waals radii. The Voronoi diagram is constructed in the 3D space by finding the voxels containing it. For the feasibility of the computation, we represent the molecule as a BVH (bounding volume hierarchy), and our system is accelerated by modern graphics hardware with CUDA programming support. Compared to single-core CPU implementations, experimental results show 323 times faster performance in the computation time, when the space is partitioned into $2^{24}$ voxels.

• Applied Biological Chemistry
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• v.46 no.4
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• pp.280-284
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• 2003

To develope of diagnosis and estimation system for utility of fungicides and insecticides as crop protection agents, various 10 physicochemical parameters, hydrophobicity (LogP), dipole moment (DM), HOMO energy, LUMO energy, molar refractivity $(MR:\;cm^3/mol)$, polarizability $(Pol:\;A^3)$, van der Waals molecular surface area $(A^2)$, van der Waals molecular volume $(Vol:\;cm^3)$, molecular weight (amu), hydration energy (Kcal/mol) for the active ingredients of 133 fungicides and 152 insecticides were calculated. And then the distribution ranges for each of the physicochemical parameters in fungicides, sterol biosynthesis inhibitors (DMI: demethylation inhibitor), insecticides and acetylcholine esterase inhibitors (AChE) were confirmed. It is suggested that the various compounds based on the range of the physicochemical parametes could be predicted for possibilities as fungicides and insecticides.

• Journal of the Korean Chemical Society
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• v.57 no.5
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• pp.540-546
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• 2013

Using the free volume of van der Waals equation, Carnahan-Starling equation for hard spheres, Wilson equation for nonrandom mixing of solution, NRTL equation and our equation, several new equations of states for pure gases are derived. Using these equations, compressibility factors for pure gases are calculated and compared with Nelson-Obert generalized compressibility factor charts. The equation of states using the concept of molecular nonrandom distribution gave better results than those of molecular random distribution. This shows that the molecular nonrandom distribution makes considerable effect on the equation of states.

• Bulletin of the Korean Chemical Society
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• v.17 no.2
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• pp.147-152
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• 1996

To see the quantitative relationship between the structures of the C-7 substituted quinolones and their antibacterial activities, theoretical parameters such as the molecular van der Waals volume, surface area and some electrostatic parameters based on the molecular electrostatic potential, which represent lipophilicity, and some quantum mechanical parameters are introduced as descriptors. The sixteen substituted quinolone derivatives and twenty bacteria are used for the study. It is found that the QSARs of C-7 substituted quinolones are obtained for eleven bacteria and our descriptors are more useful for Gram positive organisms than negative ones. It is also shown that molecular surface area (or molecular Waals volume) of the C-7 substituent and net charge of C-7 atom of the quinolones are the descriptors of utmost importance.

• Bulletin of the Korean Chemical Society
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• v.34 no.6
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• pp.1643-1650
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• 2013

A non linear QSAR model was constructed on a series of 57 xanthone and curcuminoide derivatives as ${\alpha}$-glucosidase inhibitors by back-propagation neural network method. The neural network architecture was optimized to obtain a three-layer neural network, composed of five descriptors, nine hidden neurons and one output neuron. A good predictive determination coefficient was obtained (${R^2}_{Pset}$ = 86.7%), the statistical results being better than those obtained with the same data set using a multiple regression analysis (MLR). As in the MLR model, the descriptor MATS7v weighted by Van der Waals volume was found as the most important independent variable on the ${\alpha}$-glucosidase inhibitory.

• BMB Reports
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• v.28 no.4
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• pp.363-367
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• 1995

E. coli methionyl-tRNA synthetase is one of the class I tRNA synthetases. The Tryptophane residue at the position 461 located in the C-terminal domain of the enzyme is a key amino acid for the interaction with the anticodon of $tRNA^{Met}$. W461 was replaced with other amino acids to determine the chemical requirement for the interaction with the anticodon of $tRNA^{Met}$. Saturation mutagenesis at the position 461 generated a total of 12 substitution mutants of methionyl-tRNA synthetase. All the mutants showed the same in vivo stability as the wild-type enzyme, suggesting that the amino acid substitutions did not cause severe conformational change of the protein The mutants containing tyrosine, phenylalanine, histidine and cysteine substitutions showed in vivo activity while all the other mutants did not. The comparison of the in vitro aminoacylation activities of these mutants showed that aromatic ring structure, Van der Waals volume and hydrogen bond potential of the amino acid residue at the position 461 are the major determinants for the interaction with the anticodon of $tRNA^{Met}$.