• Nuclear Engineering and Technology
• /
• v.32 no.5
• /
• pp.446-456
• /
• 2000

Laser induced photoacoustic, fluorescence, and photon correlation spectroscopies were applied to the chemical characterization of radionuclides in connection with the radiowaste treatment and disposal. Their measuring principles and systems were briefly described together with their advantages over conventional spectroscopies. Also, other applications of lasers are introduced. Laser induced photoacoustic spectra were measured for a P $r^{3+}$ solution with a very low molar absorptivity. The detection sensitivity was 4.3 $\times$10$^{-5}$ c $m^{1}$ and was 100 times better than that of a UV/VIS spectrophotometer. The Eu(III) excitation spectra($^{7}$ $F_{0}$ longrightarrow $^{5}$ $D_{0}$ transition) were measured for Eu(III)-phthalate complexes using laser fluorescence spectroscopy, showing that only two species, 1:1 and 1:2 complexes, are present in the Eu(III)-phthalic acid system. The size and size distribution for colloidal humic acids and Eu(III)-humate colloids was determined using photon correlation spectroscopy. The presence of Eu(III) enhanced the aggregation of humic acids.s.

• Bulletin of the Korean Chemical Society
• /
• v.15 no.6
• /
• pp.473-477
• /
• 1994

Second-order rate constants have been measured spectrophotometrically for the nucleophilic substitution reactions of aryl substituted benzenesulfonates $(1,\;X-C_6H_4SO_2-OC_6H_4-Y)$ with aryloxides $(Z-C_6H_4O^{-})$ and ethoxide $(EtO^-)$ in absolute ethanol at $25^{circ}C$. The nucleophilicity of aryloxides increases with increasing electron donating ability of the substituent (Z) on aryloxides, and results in a good Hammett correlation with $\sigma^{-}$ constant. The reactivity of 1 toward aryloxides and ethoxide shows also significant dependence on the electronic nature of the substituent X and Y. Large positive ${\sigma}_{acyl}$ values have been obtained for the reaction of 1 with phenoxide and ethoxide, indicating that the leaving group departure is little advanced at the transition-state of the rate-determining step. This has been further supported from the fact that ${\sigma}^-$ constant gives extremely poor Hammett correlation, while ${\sigma}^0$ does reasonably good correlation for the reaction of 1 with ethoxide. Thus, the present sulfonyl-transfer reaction is proposed to proceed via a ratedetermining attack of nucleophile to the sulfur atom of 1 followed by a fast leaving group departure.

• Bulletin of the Korean Chemical Society
• /
• v.23 no.1
• /
• pp.123-131
• /
• 2002

Solvolyses rate constant of 1- and 2- naphthoyl chlorides (1 and 2) are reported for aqueous binary mixtures with methanol, ethanol, fluorinated alcohol, acetonitrile and dioxane. Kinetic solvent isotope effects (KISE) in methanol and product selectivities (S) of 2-naphthoyl chloride (2) in alcohol-water are also reported. Dispersions in Grunwald-Winstein correlations $(r{\leq}0.901)$ are discussed by multiple regression analysis incorporating ionizing power $(Y_{Cl})$ scale and rate-rate profiles. Major causes for these phenomena are investigated as an aromatic ring solvation effects, in conjunction with weakly nucleophilic solvation effects ($S_N2$ character), for solvolyses of 1 and for solvolyses of 2, as dual reaction channels, described as $S_N1$-$S_N2$ and $S_AN$-$S_N2$ processes. Distinct border lines between the two pathways are derived from solvolyses rates of 2 in 18 solvent using the results of $log(k/k_o)=mY_{Cl}+lN_T+hI$ plot with values of 1.13 for m, 0.37 for l and 0.15 for h value in 5 aqueous fluorinated alcohol mixtures. Using rate-product correlation, the validity of a third order model based on a general base catalyzed by solvent and contribution from these rate constants, $k_{aa},\;k_{aw}$ and $k_{aw}$, are investigated for $S_AN$-$S_N2$ solvolyses of 2 favored in more rich alcohol media and gradual addition of water to alcohol solvent shows a great shift away from stoichiometric solvation to predominantly medium effects. Rate-rate correlation between solvolyses of 2 and trimethyl acetylchloride (5) with alkyl group in the 29 aqueous solvent mixtures shows appreciable linearity (slope = 0.84, r = 0.987), caused by the same pathway ($S_N1$-$S_N2$ process), even if this correlation coincides with appreciable dispersion (different solvation effect).

• KOREAN JOURNAL OF CROP SCIENCE
• /
• v.51 no.spc1
• /
• pp.58-66
• /
• 2006

The rice quality related traits including physico-chemical traits were evaluated with one hundred sixty-four MG RILs derived from the cross between Milyang 23, Indica/Japonica hybrid type, and Gihobyeo, Japonica type. The variation distribution of all traits examined approximately fit normal distribution and transgressive segregants over parents were observed for all traits. The occurrence of such transgression could be associated with the interactions of complementary QTL alleles from two parents. However in this study, it could not be concluded that our results of segregation were due to either complementary gene effects or overdominance of a major gene. These factors should be verified by further studies. Correlations between traits were evaluated by regressing phenotypic values of one trait on those of another traits. There are highly significant correlation between grain thickness with grain width, white core and white belly. But between white belly and alkali digestion value showed highly negative significant correlation. Contents of protein showed highly negative correlation with amylose and Mg/K ratio but showed highly correlation with K and Fat contents. Hardness of cooked rice showed highly correlation with adhesiveness, elasticity, gumminess, chewiness.

• Journal of the Korean Chemical Society
• /
• v.52 no.1
• /
• pp.7-15
• /
• 2008

Molecular motion influencing the absorption spectrum of a chromophore in liquid is theoretically described by a quantum mechanical time correlation function. In the present paper, we developed a theoretical method to calculate such a quantum mechanical time-correlation function from a classical time-correlation function using semi-classical approximations. The calculated time-correlation function was combined with the second order cumulant expansion method to calculate the absorption spectrum of nile blue in acetonitrile. Reasonably good agreement with experimental spectrum was obtained. From the comparison with experimental spectrum, we concluded that the time scale of solvation dynamics of the system should be longer then 1ps and the first shell of solvent is the major contribution to the solvation dynamics.

• Bulletin of the Korean Chemical Society
• /
• v.26 no.11
• /
• pp.1761-1766
• /
• 2005

Solvolysis rates of isopropenyl chloroformate (3) in water, $D_2O$, $CH_3OD$ and in aqueous methanol, ethanol, 2,2,2-trifluoroethanol (TFE), acetone, 1,4-dioxane as well as TFE-ethanol at 10 ${^{\circ}C}$ are reported. Additional kinetic data for pure water, pure ethanol and 80%(w/w) 2,2,2-trifuoroethanol (T)-water (W) at various temperatures are also reported. These rates show the phenomena of maximum rates in specific solvents (30% (v/v) methanol-water and 20% (v/v) ethanol-water) and, variations in relative rates are small in aqueous alcohols. The kinetic data are analyzed in terms of GW correlations, steric effect, kinetic solvent isotope effects (KSIE), and a third order model based on general base catalysis (GBC). Solvolyses based on predominately stoichiometric solvation effect relative to medium solvation are proceeding in 3 and the results are remarkably similar to those for p-nitrobenzoyl chloride (4) in mechanism and reactivity.

• Journal of the Korean Chemical Society
• /
• v.31 no.2
• /
• pp.153-161
• /
• 1987

The carcinogenicity of benzenoid hydrocarbons apparently depends strongly on the topological nature of the molecule. The existance of certain regions in the structure which are known propensity of benzenoid hydrocarbons to be carcinogenic. We try to identify the correlation between the number of potentially carcinogenic bay region in each of them and the quantity of Molecular Connectivity Index for 81 benzenoid hydrocarbons. Results indicate an excellent linear correlation between the number of bay region and the quantity of molecular connectivity index except the molecular containing single bond in their structure.

• Bulletin of the Korean Chemical Society
• /
• v.25 no.7
• /
• pp.1046-1050
• /
• 2004

Six physical properties (enthalpy, density, decomposition temperature, solubility in water, pKa values, and hydronium potential) were examined by molecular modeling techniques. The molecular connectivity index, Wiener distance index, and Ad hoc descriptor are employed as structural parameters to encode information about branching, size, cyclization, unsaturation, heteroatom content, and polarizability. This paper examines the correlation of the molecular modeling techniques parameters and the physicochemical properties of amino acids. As a results, calculated values were in agreement with experimental data in the above six physical properties of amino acids and the molecular connectivity index was superior to the other indices in fitting the calculated data.

• Bulletin of the Korean Chemical Society
• /
• v.24 no.8
• /
• pp.1061-1068
• /
• 2003

The correlation between the water and N-methylacetamide (NMA) intramolecular vibrational frequencies and the hydrogen-bond length in a variety of NMA-H₂O and NMA-D₂O complexes was investigated by carrying out ab initio calculations. As the hydrogen-bond length decreases, the frequencies of bending and stretching modes of the hydrogen-bonding water increases and decreases, respectively, and the amide I and II (III) mode frequencies of the NMA decreases and increases, respectively. In this paper, correlation maps among the amide (I, II, and III) modes of NMA and three intramolecular water modes are thus established, which in turn can be used as guidelines for interpreting two-dimensional vibrational spectra of aqueous NMA solutions.

• Journal of Environmental Science International
• /
• v.14 no.5
• /
• pp.463-471
• /
• 2005

This study is designed to investigate the characteristics of $PM_{10}$ concentration and the chemical composition of heavy metallic components in the $PM_{10}$ sampled in western Busan from March to May, 2003. $PM_{10}$measurement was done during springtime of 2003, totaling 29 days: 9 days in March, 10 days in April and 10 days in May. With a sampling time of 24 hours, it started 9:00 AM on that day and ended 9:00 AM the next day. The mean contribution ratio of soil during springtime was $10.3\%$. Al had a significant correlation with Ca, Fe, Mg and Si and little correlation with Na, Ni and Zn.