• Journal of the Korean Chemical Society
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• v.17 no.5
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• pp.346-352
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• 1973

The quantitative separations of a mixture containing equal amounts of each cation such as Mn(Ⅱ), Cr(Ⅲ), V(Ⅴ), Cu(Ⅱ), Ni(Ⅱ), Co(Ⅱ), and Fe(Ⅲ) are carried out by the elution through $35cm{\times}3.14cm^2$ column of cation exchange resin, $Dowex 50w{\times}12$. The eluents are a mixture of 0.6 M sodium chloride and 0.1 M sodium tartrate (pH = 2.00 and 4.50) for Fe(Ⅲ), V(Ⅴ), Cu(Ⅱ), Ni(Ⅱ) and Co(Ⅱ), and a mixture of 3 M sodium chloride and 0.1 M sodium tartrate (pH = 4.50) or a mixture of 0.7 M sodium chloride and 0.5 M sodium oxalate (pH = 4.50 and 5.00) for Mn(Ⅱ) and Cr(Ⅲ). The subsidiary cations in a standard iron mixture such as V(Ⅴ), Cu(Ⅱ), Ni(Ⅱ), Mn(Ⅱ) and Cr(Ⅲ) are separated together from the large amount of Fe(Ⅲ) through $15cm{\times}3.14cm^2$ column of the resin, $Dowex 1{\times}8$, by elution with the eluent of 4.0 M hydrochloric acid. A small amount of Fe(Ⅲ), however, is eluted together with Cu(Ⅱ). V(Ⅴ), Ni(Ⅱ), Mn(Ⅱ) and Cr(Ⅲ) eluted together are separated quantitatively through $10cm{\times}3.14cm^2$ column of the resin,$Dowex 50w{\times}12$. Cu (Ⅱ) and a small amount of Fe(Ⅲ) are separated quantitatively through $10cm{\times}3.14cm^2$ column of the resin, $Dowex 50w{\times}12$, by the elution with a mixture of 0.6 M sodium chloride and 0.1 M sodium tartrate (pH = 2.00 and 4.50) as an eluent. By the conditions obtained in the separations of the standard iron mixture, Fe(Ⅲ) and all of the subsidiary cations in steel are quantitatively separated.

• Journal of The Korean Astronomical Society
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• v.44 no.2
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• pp.49-58
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• 2011

We calculate the energy spectra of cosmic ray (CR) protons and electrons at a plane shock with quasi-parallel magnetic fields, using time-dependent, diffusive shock acceleration (DSA) simulations, including energy losses via synchrotron emission and Inverse Compton (IC) scattering. A thermal leakage injection model and a Bohm type diffusion coefficient are adopted. The electron spectrum at the shock becomes steady after the DSA energy gains balance the synchrotron/IC losses, and it cuts off at the equilibrium momentum $p_{eq}$. In the postshock region the cutoff momentum of the electron spectrum decreases with the distance from the shock due to the energy losses and the thickness of the spatial distribution of electrons scales as $p^{-1}$. Thus the slope of the downstream integrated spectrum steepens by one power of p for $p_{br}$ < p < $p_{eq}$, where the break momentum decreases with the shock age as $p_{br}\;{\infty}\;t^{-1}$. In a CR modified shock, both the proton and electron spectrum exhibit a concave curvature and deviate from the canonical test-particle power-law, and the upstream integrated electron spectrum could dominate over the downstream integrated spectrum near the cutoff momentum. Thus the spectral shape near the cutoff of X-ray synchrotron emission could reveal a signature of nonlinear DSA.

• Progress in Medical Physics
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• v.19 no.4
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• pp.256-262
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• 2008

To evaluate the metabolic changes in normal adult brains due to alterations SENSE and NEX (number of excitation) by multi voxel MR Spectroscopy at 3.0 Tesla. The study group was composed of normal volunteers (5 men and 8 women) with a mean ($\pm$ standard deviation) age of 41 (${\pm}11.65$). Their ages ranged from 28 to 61 years. MR Spectroscopy was performed with a 3.0T Achieva Release Version 2.0 (Philips Medical System-Netherlands). The 8 channel head coil was employed for MRS acquisition. The 13 volunteers underwent multi voxel spectroscopy (MVS) and single voxel spectroscopy (SVS) on the thalamus area with normally gray matter. Spectral parameters were as follows: 15 mm of thickness; 230 mm of FOV (field of view); 2000 msecs of repetition time (TR); 288 msecs of echo time (TE); $110{\times}110$ mm of VOI (view of interest); $15{\times}15{\times}15$ mm of voxel size. Multi voxel spectral parameters were made using specially in alteration of SENSE factor (1~3) and 1~2 of NEX. All MRS data were processed by the jMRUI 3.0 Version. There was no significant difference in NAA/Cr and Cho/Cr ratio between MVS and SVS likewise the previous results by Ross and coworkers in 1994. In addition, despite the alterations of SENSE factor and NEX in MVS, the metabolite ratios were not changed (F-value : 1.37, D.F : 3, P-value : 0.262). However, line-width of NAA peak in MVS was 3 times bigger than that in SVS. In the present study, we demonstrated that the alterations of SENSE factor and NEX were not critically affective to the result of metabolic ratios in the normal brain tissue.

• Journal of Korean Ophthalmic Optics Society
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• v.15 no.3
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• pp.201-206
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• 2010

Purpose: This study was to know the correlation among the dimensions of ocular components and refractive error on kindergarten children. Methods: The subjects were 80 preschool students who had no eye diseases. The refraction, corneal diopter, corneal radius, inter-pupillary distance, axial length, anterior chamber depth and dominant eye were measured and analysed. Results: It was shown that the highest correlation was between the axial length and the corneal diopter (r=-0.674, p=0.000). The ratio of height, weight and axial length (AL) to Corneal radius (CR) ratio were positively correlated with the axial length (r=0.351, r=0.408, r=0.488). The spherical equivalent of the refractive error and the corneal diopter were negatively correlated with the axial length (r=-0.302, r=-0.674). The anterior chamber depth and the corneal diopter were positively correlated with the AL/CR ratio (r=0.422, r=0.280). The spherical equivalent of the refractive error and the corneal radius were negatively correlated with the AL/CR ratio. Conclusions: It was shown that the AL/CR ratio was a very important indicator for diagnosing the refractive error of the preschoolers.

• Journal of the Korea Organic Resources Recycling Association
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• v.12 no.4
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• pp.121-129
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• 2004

Anaerobic digestion is the most common process for sewage sludge stabilization and has benefits of VS reduction and biogas production. Many pretreatment methods have been studied to improve hydrolysis rate because the rate of sewage sludge degradation is slow in anaerobic digestion. This study mainly focused upon the effects on disintegration of sewage sludge by ultrasonic pretreatment according to the variation of acoustic density and duration of sonication time. In this study, acoustic density has been changed as follows : 33W/L, 70W/L, 88W/L, 139W/L in case of 40 kHz with the test time changes of 10min, 20min, 25min, 30min and 40min. In the comparison of $SCOD_{Cr}/TCOD_{Cr}$ variation for excess sludge and mixed sludge disintegration, the rates of $SCOD_{Cr}/TCOD_{Cr}$ have been increased in the condition of denser acoustic density and longer sonication time with acoustic frequency of 40kHz. The pH of the excess sewage sludge and mixed sewage sludge has been decreased in the condition of denser acoustic density and longer sonication time with acoustic frequency of 40kHz.

• Applied Chemistry for Engineering
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• v.28 no.5
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• pp.597-600
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• 2017

$(C_{10}H_8N_2H)_2Cr_2O_7$ was synthesized by reacting 4,4'-bipyridine and chromium (VI) trioxide. The structure of the product was characterized with FT-IR (infrared spectroscopy) and elemental analysis. The oxidation of benzyl alcohol using $(C_{10}H_8N_2H)_2Cr_2O_7$ in various solvents showed that the reactivity increased with the increase of the solvent dielectric constant, in the order of DMF (N,N'-dimethylformamide) > acetone > chloroform > cyclohexane. In the presence of DMF, an acidic catalyst such as $H_2SO_4$ $(C_{10}H_8N_2H)_2Cr_2O_7$ oxidized benzyl alcohol (H) and its derivatives ($p-OCH_3$, $m-CH_3$, $m-OCH_3$, m-Cl, $m-NO_2$). Electron donating substituents accelerated the reaction rate, whereas electron acceptor groups retarded the reaction rate. Hammett reaction constant (${\rho}$) was -0.70 (308 K). The observed experimental data were used to rationalize the hydride ion transfer in the rate determining step.

• Journal of Physiology & Pathology in Korean Medicine
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• v.33 no.2
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• pp.102-108
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• 2019

This study aims to evaluate the anti-inflammatory effect of Coptidis Rhizoma (CR) extract for atopic dermatitis through maintaining skin barrier and regulating Th2 cell differentiation. We divided NC/Nga mice into 3 groups as follows; atopy-like dermatitis induced group with CR treatment (CT, n=10), no treatment group(Ctrl), atopy-like dermatitis elicited group(AE). Atopy-like dermatitis was induced to NC/Nga mice by sensitizing with dermatophagoides farinae(DfE) on 7, 8, 9, 11, 12, and 13th week. After inducing atopic dermatitis, CR extract was administered 20 mg/kg daily for the experimental duration to the CT group. We measured the integrity of lipid layers in the epidermis and Th2 differentiation through immunohistochemical staining against filaggrin, loricrin, IL-4, and IL-13. We also measured the distribution of subcutaneous collagen fibers by the Masson's trichrome staining. Administration of CR significantly inhibited the reduction of lipid layers in the skin that caused atopy. The expression of IL-4, IL-13, each of which is a cytokine secreted by T helper type 2 (Th2) cells, was markedly suppressed in the CT group as compared with AE group (p<0.05). CR treatment also decreased the expression of iNOS, $p-I{\kappa}B$. Atopic dermatitis induced dermatological damage to skin, such as hyperplasia of epithelium, and capillary proliferation was significantly reduced by CR administration. CR effectively inhibited the thinning of the skin barrier and inflammatory responses in atopic dermatitis-induced mice. In particular, it showed anti-inflammatory effects by reducing the expression of IL-4 and IL-13, Th2 cell cytokines, which play a crucial role in development of atopic dermatitis. Therefore, CR can be a good candidate to ameliorate and treat atopic dermatitis.

• Advances in environmental research
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• v.4 no.3
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• pp.197-210
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• 2015

Hexavalent chromium [Cr (VI)] adsorption on lateritic soil and lateritic soil blended with black cotton (BC) soil, marine clay and bentonite clay were studied in the laboratory using batch adsorption techniques. In the present investigation the natural laterite soil was blended with 10%, 20% and 30% BC soil, marine clay and bentonite clay separately. The interactions on test soils have been studied with respect to the linear, Freundlich and Langmuir isotherms. The linear isotherm parameter, Freundlich and Langmuir isotherm parameters were determined from the batch adsorption tests. The adsorption of Cr (VI) on natural laterite soil and blended laterite soil was determined using double beam spectrophotometer. The distribution coefficients obtained were 1.251, 1.359 and 2.622 L/kg for lateritic soil blended with 10%, 20% and 30% BC soil; 5.396, 12.973 and 48.641 L/kg for lateritic soil blended with marine clay and 5.093, 8.148 and 12.179 L/kg for lateritic soil blended with bentonite clay respectively. The experimental data fitted well to the Langmuir model as observed from the higher value of correlation coefficient. Soil pH and iron content in soil(s) has greater influence on Cr (VI) adsorption. From the study it is concluded that laterite soil can be blended with clayey soils for removing Cr (VI) by adsorption.

• Transactions of the Korean hydrogen and new energy society
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• v.10 no.3
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• pp.185-189
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• 1999

Effects of alloy modification with the $Zr_{0.6}Ti_{0.4}V_{0.4}Ni_{1.2}Mn_{0.4}$ alloy for an electrode use have been investigated. For the alloy composition, a part of Mn was substituted by Co, Cr and Fe. The experimental results showed that Co accelerated activation of alloy, and Fe and Cr improved the discharge capacity. These results agree with P-C-T curves of each alloy. But substituting Fe for Mn showed the decrease of the discharge capacity when discharged at high rate (60mA, about 1C rate). Considering both the discharge capacity and the high rate discharge property, $Zr_{0.6}Ti_{0.4}V_{0.4}Ni_{1.2}Mn_{0.3}Cr_{0.1}$ alloy was found to be the best alloy among the alloys subjected to the test.

• Carbon letters
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• v.2 no.1
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• pp.15-21
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• 2001

In this work, activated carbon fibers (ACFs) were plated with copper metal using electroless plating method and the effects of surface properties and pore structures on chromium adsorption properties were investigated. Surface properties of ACFs have been characterized using pH and acid/base values. BET data with $N_2$ adsorption were used to obtain the structural parameters of ACFs. The electroless copper plating did significantly lead to a decrease in the surface acidity or to an increase in the surface basicity of ACFs. However, all of the samples possessed a well-developed micropore. The adsorption capacity of Cr(III) for the electroless Cu-plated ACFs was higher than that of the as-received, whereas the adsorption capacity of Cr(VI) for the former was lower than that of the latter. The adsorption rate constants ($K_1$, $K_2$, and $K_3$) were also evaluated from chromium adsorption isotherms. It was found that $K_1$ constant for Cr(III) adsorption depended largely on surface basicity. The increase of Cr(III) adsorption and the decrease of Cr(VI) adsorption were attributed to the formation of metal oxides on ACFs, resulting in increasing the surface basicity.