• Korean Journal of Materials Research
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• v.28 no.7
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• pp.371-375
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• 2018

The manganese-, nickel-, and aluminum-doped cobalt ferrite powders, $Mn_{0.2}Co_{0.8}Fe_2O_4$, $Ni_{0.2}Co_{0.8}Fe_2O_4$, and $Al_{0.2}CoFe_{1.8}O_4$, are fabricated by the sol-gel method, and the crystallographic and magnetic properties of the powders are studied in comparison with those of $CoFe_2O_4$. All the ferrite powders are nano-sized and have a single spinel structure with the lattice constant increasing in $Mn_{0.2}Co_{0.8}Fe_2O_4$ but decreasing in $Ni_{0.2}Co_{0.8}Fe_2O_4$ and $Al_{0.2}CoFe_{1.8}O_4$. All the $M{\ddot{o}}ssbauer$ spectra are fitted as a superposition of two Zeeman sextets due to the tetrahedral and octahedral sites of the $Fe^{3+}$ ions. The values of the magnetic hyperfine fields of $Ni_{0.2}Co_{0.8}Fe_2O_4$ are somewhat increased in the A and B sites, while those of $Mn_{0.2}Co_{0.8}Fe_2O_4$ and $Al_{0.2}CoFe_{1.8}O_4$ are decreased. The variation of $M{\ddot{o}}ssbauer$ parameters is explained using the cation distribution equation, superexchange interaction and particle size. The hysteresis curves of the ferrite powders reveal a typical soft ferrite pattern. The variation in the values of saturation magnetization and coercivity are explained in terms of the site distributions, particle sizes and the spin magnetic moments of the doped ions.

• Nuclear Engineering and Technology
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• v.51 no.8
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• pp.2005-2012
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• 2019

This work investigated the radiation attenuation characteristics of three series of tellurite glass systems with the following compositions: 30PbO-10ZnO-xTeO₂-(60-x)B₂O₃ where x = 10, 30, 40, 50 and 60 mol%, xBaO-xB₂O₃-(100-2x)TeO₂ with x = 15-40 mol% and 50ZnO-(50-x)P₂O₅-xTeO₂, where x = 0, 10, .40 mol%. The results revealed that the attenuation parameters in all the samples decrease with increase in the energy, which implied that all the samples have better interaction with gamma photons at low energies and thus higher photon attenuating efficiency. From the three systems, the samples coded as PbZnBTe60, BaBTe70 and ZnPTe40 have the lowest half value layer values and accordingly have superior photon attenuation efficacy. The maximum effective atomic number values were found for energy less than 0.1 MeV particularly near the K-edges absorption of the heavy atomic number elements such as Te, Ba and Pb. At the lowest energy, the Z_eff values are found in the range of 62.33-66.25, 49.43-50.81 and 24.99-35.83 for series 1-3 respectively. Also, we found that the density of the glass remarkably affects the photon attenuation ability of the selected glasses. The mean free path results showed that the PbO-ZnO-TeO₂-B₂O₃ glass system has better radiation shielding efficiency than the glass samples in series 2 and 3.

• Archives of Pharmacal Research
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• v.28 no.10
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• pp.1196-1202
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• 2005

Omeprazole (OMP) is a proton pump inhibitor used as an oral treatment for acid-related gastrointestinal disorders. In the liver, it is primarily metabolized by cytochrome P-450 (CYP450) isoenzymes such as CYP2C19 and CYP3A4. 5-Hyroxyomeprazole (5-OHOMP) and omeprazole sulfone (OMP-SFN) are the two major metabolites of OMP in human. Cimetidine (CMT) inhibits the breakdown of drugs metabolized by CYP450 and reduces, the clearance of coad-ministered drug resulted from both the CMT binding to CYP450 and the decreased hepatic blood flow due to CMT. Phenobarbital (PB) induces drug metabolism in laboratory animals and human. PB induction mainly involves mammalian CYP forms in gene families 2B and 3A. PB has been widely used as a prototype inducer for biochemical investigations of drug metabolism and the enzymes catalyzing this metabolism, as well as for genetic, pharmacological, and toxicological investigations. In order to investigate the influence of CMT and PB on the metabolite kinetics of OMP, we intravenously administered OMP (30 mg/kg) to rats intraperitoneally pretreated with normal saline (5 mL/kg), CMT (100 mg/kg) or PB (75 mg/kg) once a day for four days, and compared the pharmacokinetic parameters of OMP. The systemic clearance ($CL_{t}$) of OMP was significantly (p<0.05) decreased in CMT-pretreated rats and significantly (p<0.05) increased in PB-pretreated rats. These results indicate that CMT inhibits the OMP metabolism due to both decreased hepatic blood flow and inhibited enzyme activity of CYP2C19 and 3A4 and that PB increases the OMP metabolism due to stimulation of the liver blood flow and/or bile flow, due not to induction of the enzyme activity of CYP3A4.

• Journal of the Korean Chemical Society
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• v.54 no.4
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• pp.374-379
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• 2010

The interaction of dichlorophenol isomers with the micellar system of TTAB (tetradecyltrimethylammonium bromide) was studied by the UV/Vis spectrophotometric method. The solubilization constants ($K_s$) of dichlorophenol isomers into the micellar system have been measured with the change of temperature and the various thermodynamic parameters have been calculated and analyzed from these changes. The results show that the values of ${\Delta}G^{\circ}_s$ and ${\Delta}H^{\circ}_s$ are all negative within the measured temperature range. The effects of additives (n-butanol and NaCl) on the solubilization of dichlorophenol isomers have been also measured. There was a great change on the values of $K_s$ and CMC simultaneously with these additives. From these changes we can postulate the solubilization sites of each isomers in the micellar system of TTAB.

• Bulletin of the Korean Chemical Society
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• v.34 no.11
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• pp.3199-3205
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• 2013

The inclusion behavior of sulfobutylether-${\beta}$-cyclodextrin (SBE-${\beta}$-CD) with perphenazine (PPH) was first studied by flow injection (FI)-chemiluminescence (CL) analysis with proposed $lg[(I_0-I_s)/I_s]=lgK_{P-CD}+nlg[C_{PPH}]$ model and molecular docking. Results showed that a 1:1 complex of SBE-${\beta}$-CD/PPH could online form, with the formation constant $K_{P-CD}$ of $2.57{\times}10^7Lmol^{-1}$ at 298 K. The thermodynamic parameters showed that the inclusion behavior of SBE-${\beta}$-CD/PPH was a spontaneous process by hydrophobic interaction. The molecular docking results revealed PPH entered into the larger cavity of SBE-${\beta}$-CD with two hydrogen bonds. Based on the linear relationship of the decrement of luminol/SBE-${\beta}$-CD/PPH CL intensity against the logarithm of PPH concentration ranging from 0.03 to 30.0 ng $mL^{-1}$, the present FI-CL analysis using luminol/SBE-${\beta}$-CD/PPH system was successfully applied to PPH determination in biological fluids and tablets with recoveries from 94.5 to 105.6% and RSDs less than 2.6% (n = 5).

• International Journal of High-Rise Buildings
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• v.9 no.3
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• pp.273-282
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• 2020

An innovative high-rise timber-concrete hybrid structure was proposed in previous research, which is composed of the concrete frame-tube structure and the prefabricated timber modules as main structure and substructures, respectively. Considering that the timber substructures are built on the concrete floors at a different height, the floor response spectrum is more effective in estimating the seismic response of substructures. In this paper, the floor response spectra of the hybrid structure with different structural parameters were calculated using dynamic time-history analysis. Firstly, one simplified model that can well predict the seismic response of the hybrid structure was proposed and validated. Then the construction site, the mass ratio and the frequency ratio of the main-sub structure, and the damping ratio of the substructures were discussed. The results demonstrate that the peaks of the floor response spectra usually occur near the vibration periods of the whole structure, among which the first two peaks stand out; In most cases, the acceleration amplification effect on substructures tends to be more evident when the construction site is farther from the fault rupture; On the other hand, the acceleration response of substructures can be effectively reduced with an appropriate increase in the mass ratio of the main-sub structure and the damping ratio of the substructures; However, the frequency ratio of the main-sub structure has no discernible effect on the floor response spectra. This study investigates the characteristics of the floor response spectrum of the novel timber-concrete structure, which supports the future applications of such hybrid structure in high-rise buildings.

• Journal of the Korean Chemical Society
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• v.36 no.4
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• pp.589-597
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• 1992

The rate constants of hydrolysis of phenyl-N-benzoylchlorothioformimidates were determined by UV spectrophotometry in 30% (v/v) aqueous dioxane at $25^{\circ}C$. On the basis of rate equation, general base catalysis, solvent effect, substituent effect, thermodynamic parameters, frontier orbital interaction and hydrolysis product analysis, it may be concluded that the hydrolysis of phenyl-N-benzoylchlorothioformimidates proceeds through $S_N1$ mechanism via azocarbocation intermidiate below pH 10.0, while above pH 10.00 the hydrolysis proceeds through nucleophilic addition-elimination ($Ad_{N-E}$) mechanism. In the range of pH from 10.0 to 11.0 these two reaction occur competitively.

• Nuclear Engineering and Technology
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• v.28 no.1
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• pp.44-55
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• 1996

For the purpose of controlling the release of radioiodine to the environment in nuclear power plants, adsorption characteristics of elemental iodine and methyl iodide on the base carbon and 2%, 5% TEDA impregnated carbons were studied. The amounts of adsorption of elemental iodine and methyl iodide on the carbons were compared with Langmuir, Freundlich, Sips and Dubinin-Astakhov(DA) isotherm equations. Adsorption data were well correlated by the DA equation based on the potential theory. Adsorption energy distributions were obtained from the parameters of the DA equation derived from the condensation approach method. For the adsorption of methyl iodide and elemental iodine-carbon system, the DA equation can be well expressed by the degree of heterogeneity of the micropore system because the surface is nonuniform when its potential energy is unequal. The adsorption energy distribution wes investigated to find a surface heterogeneity on the carbon. The surface heterogeneity for iodine-carbon system is highly affected by the adsorbate-adsorbent interaction as well as the pore structure. The surface heterogeneity increases as a content of TEDA impregnated increases. The adsorption nature of methyl iodide on carbon turned out to be more heterogeneous than that of elemental iodine.

• Journal of Microbiology and Biotechnology
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• v.28 no.6
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• pp.917-930
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• 2018

Intracellular synthesis of silver/silver chloride nanoparticles (Ag/AgCl-NPs) using Meyerozyma guilliermondii KX008616 is reported under aerobic and anaerobic conditions for the first time. The biogenic synthesis of Ag-NP types has been proposed as an easy and cost-effective alternative for various biomedical applications. The interaction of nanoparticles with ethanol production was mentioned. The purified biogenic Ag/AgCl-nanoparticles were characterized by different spectroscopic and microscopic approaches. The purified nanoparticles exhibited a surface plasmon resonance band at 419 and 415 nm, confirming the formation of Ag/AgCl-NPs under aerobic and anaerobic conditions, respectively. The planes of the cubic crystalline phase of the Ag/AgCl-NPs were confirmed by X-ray diffraction. Fourier-transform infrared spectra showed the interactions between the yeast cell constituents and silver ions to form the biogenic Ag/AgCl-NPs. The intracellular Ag/AgCl-NPs synthesized under aerobic condition were homogenous and spherical in shape, with an approximate particle size of 2.5-30nm as denoted by the transmission electron microscopy (TEM). The reaction mixture was optimized by varying reaction parameters, including temperature and pH. Analysis of ultrathin sections of yeast cells by TEM indicated that the biogenic nanoparticles were formed as clusters, known as nanoaggregates, in the cytoplasm or in the inner and outer regions of the cell wall. The study recommends using the biomass of yeast that is used in industrial or fermentation purposes to produce Ag/AgCl-NPs as associated by-products to maximize benefit and to reduce the production cost.

• International journal of advanced smart convergence
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• v.5 no.4
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• pp.15-20
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• 2016

When a virtual sound source for 3D auditory system is reproduced by a linear loudspeaker array, listeners can perceive not only the direction of the source, but also its distance. Control over perceived distance has often been implemented via the adjustment of various acoustic parameters, such as loudness, spectrum change, and the direct-to-reverberant energy ratio; however, there is a neglected yet powerful cue to the distance of a nearby virtual sound source that can be manipulated for sources that are positioned away from the listener's median plane. This paper address the problem of generating binaural signals for moving sources in closed or in open environments. The proposed perceptual enhancement algorithm composed of three main parts is developed: propagation, reverberation and the effect of the head, torso and pinna. For propagation the effect of attenuation due to distance and molecular air-absorption is considered. Related to the interaction of sounds with the environment, especially in closed environments is reverberation. The effects of the head, torso and pinna on signals that arrive at the listener are also objectives of the consideration. The set of HRTF that have been used to simulate the virtual sound source environment for 3D auditory system. Special attention has been given to the modelling and interpolation of HRTFs for the generation of new transfer functions and definition of trajectories, definition of closed environment, etc. also be considered for their inclusion in the program to achieve realistic binaural renderings. The evaluation is implemented in MATLAB.