• Title/Summary/Keyword: binding constant

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Effect of Addition of Dietary Fibers on Quality of Backsulgies (식이섬유 첨가에 의한 백설기의 특성변화에 관한 연구)

  • Choi, In-Ja;Kim, Young-A
    • Korean journal of food and cookery science
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    • v.8 no.3
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    • pp.281-289
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    • 1992
  • The physicochemical, rheological and sensory characteristics of Backsulgies added with dietary fibers-cellulose, pectin and wheat bran-were investigated. The maximum acceptable ratio of fibers was 10% for wheat bran or cellulose, 3% for pectin. As me results of physicochemical analysis, cellulose and pectin had larger water-binding capacity man wheat bran. Swelling power was increased with temperature increment. But the type of added dietary fiber did not make significant differences. The degree of gelatinization was measured by maltose content. The retrogradation of backsulgies was significantly delayed by the addition of dietary fibers. The retardation effect of dietary fibers for retrogradation of backsulgies was also proved by textural analysis and time constant determination of Avrami equation. Pectin had especially excellent delaying effect while me storage time extended. There were no significant differences in sensory characteristics between me backsulgi with no dietary fibers and backsulgies added with cellulose 3%, pectin 1% and wheat bran 3%. Therefore, we concluded mat cellulose 3%, pectin 1% and wheat bran 3% were me optimum addition ratios, which have the delaying effect of retrogradation, and which could be accepted as same as conventional backsulgies organoreptically.

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Determination of Heparin Using Norfloxacin-cerium Complex as a Fluorescence Probe by Spectrofluorimetry

  • Patil, Shailaja R.;Mote, Umesh S.;Patil, Shivajirao R.;Kolekar, Govind B.
    • Bulletin of the Korean Chemical Society
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    • v.30 no.12
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    • pp.3034-3038
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    • 2009
  • A simple, rapid, practical and sensitive spectofluorimetric method was developed for the determination of trace amount of heparin (Hep). Under the Optimum conditions, we studied the interaction between NFLX-Ce$^{3+}$-Hep complex by using absorption and fluorescence spectra. It was observed that Hep remarkably enhance the fluorescence intensity of the NFLX-Ce$^{3+}$ complex at ${\lambda}$= 356 nm in the buffer solution of pH = 7.60 and the enhancement effect is shown to relate with the concentration of Hep. The linear range and detection limit for the determination of Hep was obtained. By the Rosenthal graphic method, the association constant (K) and binding numbers (N) of Hep with probe were investigated. This method is relatively free of interference from coexisting substances and successfully applied for the determination of heparin in heparin sodium injection samples. A suitable mechanism of fluorescence enhancement between NFLX-Ce$^{3+}$ and the NFLX-Ce$^{3+}$-Hep systems were proposed and discussed.

Molecular Dissection of the Interaction between hBLT2 and the G Protein Alpha Subunits

  • Vukoti, Krishna Moorthy;Lee, Won-Kyu;Kim, Ho-Jun;Kim, Ick-Young;Yang, Eun-Gyeong;Lee, Cheol-Ju;Yu, Yeon-Gyu
    • Bulletin of the Korean Chemical Society
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    • v.28 no.6
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    • pp.1005-1009
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    • 2007
  • Leukotriene B4 (LTB4) is a potent chemoattractant for leukocytes and considered to be an inflammatory mediator. Human BLT2 (hBLT2) is a low-affinity G-protein coupled receptor for LTB4 and mediates pertussis toxin-sensitive chemotactic cell movement. Here, we dissected the interaction between hBLT2 and G-protein alpha subunits using GST fusion proteins containing intracellular regions of hBLT2 and various Gα protein including Gα i1, Gα i2, Gα i3, Gα s1, Gα o1, and Gα z. Among the tested Gα subunits, Gα i3 showed the highest binding to the third intracellular loop region of hBLT2 with a dissociation constant (KD) of 5.0 × 10?6 M. These results suggest that Gα i3 has the highest affinity to hBLT2, and the third intracellular loop region of hBLT2 is the major component for the interaction with Gα i3.

Properties of SiOCH Thin Film Lour Dielectric by BTMSM/O2 Flow Rates (BTMSM/O2 유량변화에 따른 SiOCH 박막의 저유전 특성)

  • Park, In-Cheol;Kim, Hong-Bae
    • Journal of the Korean Institute of Electrical and Electronic Material Engineers
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    • v.22 no.2
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    • pp.132-136
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    • 2009
  • SiOC thin film of hybrid-type that is the limelight as low dielectric material of next generation were deposited by plasma enhanced chemical vapor deposition (PECVD) method with bistrimethylsilylmethane (BTMSM) precursor increased by 2 sccms from 24 sccms to 32 sccm. Manufactured samples are analyzed components by measuring FT/IR absorption lines. It is a tendency that seems to be growing of Si-O-Si(C) bonding group and narrowing of Si-O-$CH_3$ bonding group relative to the increasing flow-rate BTMSM. The chemical shift in the XPS analysis was shown in the specimens between the BTMSM=26 sccm and BTMSM = 28 sccm. The binding energy of Si 2p, C 1s and O 1s electron orbit spectra was the low-est at the specimen of the BTMSM=26 sccm. From the results of electrical Properties using the 1 MHz C - V measurements, the dielectric constant was 2.32 at the specimen with the BTMSM = 26 sccm.

Influence of RTA treatments on optical properties of ZnO nanorods synthesized by wet chemical method

  • Shan, Qi;Ko, Y.H.;Lee, H.K.;Yu, J.S.
    • Proceedings of the Korean Vacuum Society Conference
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    • 2010.02a
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    • pp.190-190
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    • 2010
  • Zinc oxide is the most attractive material due to the large direct band gap (3.37 eV), excellent chemical and thermal stability, and large exciton binding energy (60 meV). Recently, ZnO nanorods were used as the high efficient antireflection coating layer of solar cells based on silicon (Si). In this reports, we studied the effects of rapid thermal annealing (RTA) treatment on optical properties of ZnO nanorods. For fabrication of ZnO nanorods, there are many methods such as hydrothermal method, sol-gel method, and metal organic chemical vapor deposition method. Among of them, we used the conventional wet chemical method which is simple and low temperature growth. In order to synthesize the ZnO nanorods, the ZnO films were deposited on Si substrate by RF magnetron sputtering at room temperature and the samples were dipped to aqua solution containing the zinc nitrate and hexamethylentetramines (HMT). The synthesis process was achieved in keeping with temperature of $90-95^{\circ}C$ and under constant stirring. The morphology of ZnO nanorods on glass and Si was characterized by scanning electron microscopy. For the analysis of antireflection performance, the reflectance and transmittance were measured by spectrophotometer. And for analyzing the effects of RTA treatment on ZnO nanorods, crystalline properties were investigated by X-ray diffraction measurements and optical properties was estimated by photoluminescence spectra.

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A Study on the Effect of Addition of Dietary Fibers on Quality of Julpyun (식이섬유 첨가가 절편의 특성에 미치는 영향에 관한 연구)

  • Lee, Ji-Young;Koo, Sung-Ja
    • Korean journal of food and cookery science
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    • v.10 no.3
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    • pp.267-276
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    • 1994
  • Recent epidemological observations suggested beneficial effects of dietary fiber on man's health. With the increased emphasis placed on the requirement for dietary fiber in the diet, there has been greater interest in successfully incorporating dietary fiber into food products. Hence, in this study, several dietary fibers such as cellulose, pectin, rice bran, barley bran and job's tears bran were incorporated into julpyun to determine their effects on some physical properties and sensory characteristics. Difference of water binding capacity(WBC) was found among dietary fiber sources. The WBC of pectin was highest and that of job's tears bran was lowest. The moisture contents of julpyun were increased as WBC of added dietary fiber sources was higher. In the rheometer measurement for julpyun added with dietary fiber, hardness of julpyuns added with cellulose and pectin was low. But, hardness of julpyun added cellulose was increased rapidly during storage at 4$^{\circ}C$. Springiness and gumminess wereshowed similar aspects to hardness. In the retrogradation speed by Avrami equation, the rate constant of julpyun added barley bran was low ao retrogradation occurred slowly. The results of sensory evaluation, julpyun added no dietary fiber showed good overall preference. Overall preference in sensory evaluation showed positive correlation with the after-swallowing and color.

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Properties of Sodium Dodecyl Sulfate / Triton X-100 Mixed Micelle

  • Park, Joon-Woo;Chung, Myung-Ae;Choi, Kyung-Moon
    • Bulletin of the Korean Chemical Society
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    • v.10 no.5
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    • pp.437-442
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    • 1989
  • The cmc's of sodium dodecyl sulfate (SDS)/Triton X-100 surfactant mixtures were determined by surface tension measurement at various surfactant compositions. The cmc values were lower than those predicted from ideal mixture. The regular solution theory was applied to calculate the interaction parameter, micellar composition, and the activity coefficients of surfactants in the mixed micelle. The interaction parameter (${\beta}$) was - 2.1. The nonideality arised largely from decreased activity of SDS in the mixed micelle. The mean aggregation numbers (${\bar{n}}$) and micropolarity of hydrocarbon region of the mixed micelles were determined by luminescence probe techniques. The total aggregation number (${\bar{n}}_{SDS}+{\bar{n}}_{TX}$) in mixed micelles showed little dependency on the composition of the micelle. The apparent dielectric constant of the hydrocarbon region of the micelle vs micellar composition plot showed positive deviation from linearity. Emission and emission quenching of excited tris(2,2'-bipyridine)ruthenium(Ⅱ) cation, $(Ru(bpy)_3^{2+})$, by methylviologen ($MV^{2+}$) were also investigated in the mixed micellar solutions. The quenching rate was lowest when the mole fraction of SDS in the surfactant mixtures (${\alpha}_{SDS}$) is about 0.25 and highest at ${\alpha}_{SDS}$ = 0.85. This was explained in terms of combined effects of binding of the cations with the micelle and mobility of the bound cations on the surface of the micelles.

Disappearance of the ${\alpha}$-Effect : Reaction of p-Nitrophenyl Acetate with Various Aryloxides and Benzohydroxamates in the Presence of Cetyltrimethylammonium Bromide

  • Dong Sook Kwon;Seung Eun Lee;Jin Kyung Jung;Jong Yoon Park;Ik Hwan Um
    • Bulletin of the Korean Chemical Society
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    • v.13 no.5
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    • pp.486-491
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    • 1992
  • The rate constants for the reactions of p-nitrophenyl acetate with 6 different aryloxides and 2 benzohydroxamates have been measured spectrophotometrically in water containing various concentrations of cetyltrimethylammonium bromide (CTAB). The reactivity of the nucleophiles has been demonstrated to be significantly enhanced as the concentration of the surfactant increases up to a certain point. When the basicities of the aryloxides are comparable, the rate enhancement is more prominent for the aryloxide having larger binding constant to the micellar aggregate. Benzohydroxamates exhibitis significantly large ${\alpha}$-effect in the absence of the surfactant, although, the ${\alpha}$-effect nucleophiles are considered to be more solvated in water than the corresponding normal nucleophile. Thus, the solvation effect does not appear to be solely responsible for the ${\alpha}$-effect. Interestingly, the large ${\alpha}$-effect disappears in the presence of the surfactant. Therefore, one might attribute the disappearance of the ${\alpha}$-effect to solvent effect. However, a structural change of the reactive ${\alpha}$ -effect nucleophile into unreactive ones would also be considered to be responsible for the absence of the ${\alpha}$-effect in the present system.

Fluorescence Spectroscopy Studies on Micellization of Poloxamer 407 Solution

  • Lee, Ka-Young;Shin, Sang-Chul;Oh, In-Joon
    • Archives of Pharmacal Research
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    • v.26 no.8
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    • pp.653-658
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    • 2003
  • It has been reported that at low temperature region, poloxamers existed as a monomer. Upon warming, an equilibrium between unimers and micelles was established, and finally micelle aggregates were formed at higher temperature. In this study, the fluorescence spectroscopy was used to study the micelle formation of the poloxamer 407 in aqueous solution. The excitation and emission spectra of pyrene, a fluorescence probe, were measured as a function of the concentration of poloxamer 407 and temperature. A blue shift in the emission spectrum and a red shift in the excitation spectrum were observed as pyrene transferred from an aqueous to a hydrophobic micellar environment. From the $I_1/I_3 and I_{339}/I_{333}$ results, critical micelle concentration (cmc) and critical micelle temperature (cmt) were determined. Also, from the fluorescence spectra of the probe molecules such as 8-anilino-1-naphthalene sulfonic acid and 1-pyrenecarboxaldehyde, the blue shift of the $\lambda_{max}$ was observed. These results suggest a decrease in the polarity of the microenvironment around probe because of micelle formation. The poloxamer 407 above cmc strongly complexed with hydrophobic fluorescent probes and the binding constant of complex increased with increasing the hydrophobicity of the probe.

The Effect of Ions on Thermal Behaviors of Water in Poly(acrylic acid)/Water Mixtures (폴리아크릴산/$H_2O$ 혼합물에서 $H_2O$ 열적 거동에 미치는 이온의 영향)

  • Guan, Lan;Xu, Hongyan;Huang, Dinghai
    • Polymer(Korea)
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    • v.34 no.4
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    • pp.386-389
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    • 2010
  • Thermal behaviors of water in the poly(acrylic acid) (PAA)/water mixtures with 0.1 M NaCl, HCl, and NaOH were investigated by DSC. It showed that adding ions in the mixtures affected the crystallization of water evidently. Compared with the PAA/water mixtures, the $T_m$ of freezable bound water in the mixtures with ions moved to lower values and varied with different cations and anions, due to the stabilization or destabilization of the hydrogen-bonding hydration between polymers and water molecules through ionic hydration. The content of non-freezable bound water in the non-crystalline phase of the PAA/water mixtures with ions was not constant, it increased with total water content gradually, owing to the more binding sites created by ions. The ions could change the distribution of different states of water in the polymer aqueous solutions evidently.