Showing papers by "Korea University published in 1983"

Relationship between fluorescence and antioxidant activity of ethanol extracts of a maillard browning mixture

Abstract: The relationship between the color and fluorescence of a Maillard browning mixture (0.1M glucose+0.1M glycine, heated at 100 C) and the antioxidant activity of ethnol extracts of the mixture was investigated. The activity was estimated by comparing the peroxide value development of soybean oil substrates containing the extracts with that of a control. The excitation and emission maxima of the mixture were 365 and 440 nm, and those of the extract 367 and 430 nm. The relative fluorescence (that of 1 µg quinine sulfate/mL 0.01N H2SO4=100) of the mixture after 16 hr browning was 450, whereas that of the corresponding extract was 175.8. The fluorescence of the mixture increased in parallel to the color (absorbance at 490 nm), which, in turn, was almost proportional to reaction time, except at the earlier stages of browning. The change of the fluorescence with the reaction time at the earlier stages was far greater than that of the absorbance at the same stages. Determination of fluorescence seems to provide a more sensitive method for tracing early browning than that of absorbance. The ethanol extracts from very early stages of the browning exhibited considerable antioxidant activity, and, unlike the absorbance of the mixture or the fluorescence of the extract, the activity of the extract changed very little with the reaction time. It appears that effective antioxidants with almost no color but with considerable fluorescence were already formed at the earlier stages of browning.

Analysis of turbulent gas-solid suspension flow in a pipe

Abstract: The mixing length theory is extended to close the relevant momentum equations for two-phase turbulent flow at a first-order closure level. It is assumed that the mass fraction of the particles is on the order of unity, that the particle size is so small that the particles are fully suspended in the primary fluid, and that the relaxation time scale of the particles is sufficiently small compared with the time scale of the energy containing eddies so that the suspended particles are fully responsive to the fluctuating turbulent field. Bulk motion of the particles is treated as a secondary fluid flow with its own virtual viscosity. The proposed closure is applied to a fully developed gas-solid pipe flow in which the particles are assumed to be uniformly distributed across the pipe section. Predicted velocity profiles and the friction factors are in good agreement with available experimental data.

Contents of Sugars, Fruit Acids, Amino Acids and Phenolic Compounds of Apple Fruits i n Relation to their Susceptibility to Botryosphaeria ribis

Abstract: Five apple cultivars showing different levels of susceptibility to Botryosphaeria ribis were used to study the relationship between susceptibility and contents of sugars, fruit acids, amino acids and phenolic compounds in the fruits at various stages of maturity. Immature fruits of all the cultivars tested were completely resistant until 10 July. The fungus grew better on the yellow-coloured cultivars than the red-coloured cultivars. The low amount of reducing sugars and also the high levels of fruit acids, amino acids and total phenols were found in immature apple fruits, irrespective of cultivar. No consistent differences between the cultivars were recognized with regard to the contents of soluble sugars, fruit acids and phenols in fruit flesh during the maturity of fruits. However, only the levels of total soluble amino acids in fruit flesh and of total phenols in fruit peel at late stage of maturity consistently varied between the cultivars. The dark red-coloured, resistant cultivars Miller spur and Starkrimson showed higher contents of amino acids and phenols in fruit tissues than did the yellow-coloured, susceptible cultivars. Zusammerifassung Gehalt an Zudcer, Fruchtsauren, Aminosauren und phenolischen Substanzen in Apfelfruchten im Zusammenhang mit der Anfalligkeit gegenuber Botryosphaeria ribis Der Zusammenhang zwischen Anfalligkeit gegenuber Botryosphaeria ribis und den Ge-halt an Zucker, Fruchtsauren, Aminosauren und phenolischen Substanzen in verschiedenen Reifestadien der Apfelfruchte wurde an Friichten von fiinf Apfelsorten mit untersdiiedlicher Anfalligkeit untersudit. Die unreifen Friidite aller gepriiften Sorten waren bis zum 10. Juli vollstandig resistent. Auf den gelbfarbigen Sorten wuchs der Pilz besser als auf den rotlarbigcn. Ungeachtct der Sorte wurden niedrige Gehalte an reduzierenden Zuckern, aber hohe Gciialto an I-ruditsaftcn, Aminosauren und Phenolen in unreifen Apfelfruchten gefunden. Hinsichtlidi des Gchaltcs an loslichen Zuckern, Fruchtsauren und Phenolen im Frudit-tlcisch wahrend der Fruditrcife waren keine stetigen Unterschiede zwischen den Sorten zu erkennen. jedocK waren die Niveaus der gesamten loslichen Aminosauren im Fruchtfleisdi und der gesanuen phenolischen Substanzen in der Fruchtsdiale wahrend der Fruditreife zwisdien den Sorten durdiweg verschieden. Die dunkelroi:farbigen, resistenten Sorten Miller spur und Stark Starkrimson zeigten hohere Gehalte an Aminosauren und Phenolen im Fruchtgewebe als die gelbfarbigen Sorten.

Solubility and diffusion of hydrogen in amorphous CuTi alloys

Abstract: Amorphous alloys of the CuTi binary system were prepared by a rapid quenching method and their characteristics such as crystallization temperature, electrical resistivity, density and Vickers' hardness were measured. The diffusion of hydrogen in two groups of specimens, i.e. amorphous CuTi alloys and the crystalline TiH2Cu phase produced by the decomposition of the CuTiH system, was investigated using the evolution method. The results showed that the activation energy for the evolution of hydrogen was dependent on the composition of the binary CuTi alloys.

Diffusion of hydrogen in amorphous Cu45Ti55 ribbon

Abstract: The diffusion of hydrogen in amorphous Cu 45 Ti 55 ribbon and in a crystalline TiH 2 Cu phase produced by the decomposition of Cu 45 Ti 55 H x was investigated in the temperature range 360–583 K using the evolution method. The rate of evolution of hydrogen was related to the amount of hydrogen absorbed in the amorphous specimens. The activation energy for the rate of evolution of hydrogen was much larger in the crystalline TiH 2 Cu phase than in the amorphous phase.

Microstructure and Hydrodynamic Properties of Soybean Protein Bodies in Solutions

Abstract: The changes in the size and shape of soybean protein bodies in different solvent systems were observed, and their influence on hydrodynamic properties in solutions was investigated by capillary viscometer. The intrinsic viscosity of the isolated protein bodies varied with the type of dispersion media; 0.036 cm3/g in CCI4-benzene solution, 0.355 cm3/g in 50% glycerol-water mixture, 0.574 cm3/g in water at pH 7, and 1.18 cm3/g in the aqueous solution at pH 12. The hydration of the protein bodies in different dispersion media was estimated by Oncley's method and Mooney's method. The estimated degree of hydration agreed well with the swelling of the protein bodies as observed by microscope.

Intravesical instillation therapy with adriamycin for bladder cancer in the Korean study group.

Abstract: Eighteen cases of bladder cancer were treated with intravesical instillation therapy with 60 mg Adriamycin daily. Overall, the treatment was markedly effective in two cases, effective in nine cases, and ineffective in seven cases. Bladder irritation was noted in four cases. Postinstillation therapy was required in most cases.

Third sound and energy dispersion of helium films

Abstract: Adopting a soft potential, we have made a microscopic approach to the velocity of third sound in liquid $^{4}\mathrm{He}$ films and derived an explicit formula for its temperature variation. This formula explains the temperature dependence of third sound without ad hoc assumptions such as those used by Rutledge, McMillan, Mochel, and Washburn. In particular, the source of the temperature dependence of the coefficient to the ${T}^{3}$ term which resulted from their approach is naturally explained.

Alternating copolymerization of diethyl α-phenylvinyl phosphate and maleic anhydride

Abstract: The kinetics of the free-radical copolymerization of diethyl α-phenylvinyl phosphate (DEPVP, M2) and maleic anhydride (MAnh, M1) in chloroform were studied using benzoyl peroxide as an initiator. The generalized model was successfully applied to determine the reactivity ratios k1c/k12 and k2c/k21 from the change in copolymerization rate with monomer feed at a constant total monomer concentration. The copolymerization was found to proceed via two pathways, one involving formation of a charge-transfer complex between the two monomers and the other involving the two free monomers. A kinetic analysis indicated that the rate of formation of the MAnh free radical, k1ck21, was slightly slower than that of the DEPVP free radical, k2ck12, and that the copolymerization proceeded predominantly through participation of the free monomers rather than the charge-transfer complex. General kinetic studies at various initiator concentrations showed the overall copolymerization rate to depend on an order of 0.49 with respect to the initiator concentration. The overall activation energy for this copolymerization was found to be 33.5 kJ mol−1.