• Advances in nano research
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• v.12 no.6
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• pp.605-616
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• 2022

We prepared two samples of ultrafine ferrihydrite (FH) nanoparticle ensembles of quite a different origin. First is the biosynthesized sample (as a product of the vital activity of bacteria Klebsiella oxytoca (hereinafter marked as FH-bact) with a natural organic coating and negligible magnetic interparticle interactions. And the second one is the chemically synthesized ferrihydrite (hereinafter FH-chem) without any coating and high level of the interparticle interactions. The interparticle magnetic interactions have been tuned by modifying the nanoparticle surface in both samples. The coating of the FH-bact sample has been partially removed by annealing at 150℃ for 24 h (hereinafter FH-annealed). The FH-chem sample, vice versa, has been coated (1.0 g) with biocompatible polysaccharide (arabinogalactan) in an ultrasonic bath for 10 min (hereinafter FH-coated). The changes in the surface properties of nanoparticles have been controlled by XPS. According to the electron microscopy data, the modification of the nanoparticle surface does not drastically change the particle shape and size. A change in the average nanoparticle size in sample FH-annealed to 3.3 nm relative to the value in the other samples (2.6 nm) has only been observed. The estimated particle coating thickness is about 0.2-0.3 nm for samples FH-bact and FH-coated and 0.1 nm for sample FH-annealed. Mössbauer and magnetization measurements are definitely shown that the drastic change in the blocking temperature is caused by the interparticle interactions. The experimental temperature dependences of the hyperfine field hf>(T) for samples FH-bact and FH-coated have not revealed the effect of interparticle interactions. Otherwise, the interparticle interaction energy E_int estimated from the hf>(T) for samples FH-chem and FH-annealed has been found to be 121k_B and 259k_B, respectively.

• Applied Biological Chemistry
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• v.32 no.3
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• pp.240-248
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• 1989

The effects of the soil properties on the contents of catalpol, sugar and ash in the rhizoma of Ji-whang (Rehmannia glutinosa Lib. var. purpurea Makino) were studied to get information on cultivation for higher quality production. Catalpol contents of the rhizoma of Ji-whang ranged from 3.75 to 4.36%. It was shown that the sand contents of soil was positively correlated with the catalpol contents, and negatively correlated with the contents of fructose and galactose in the rhizoma of Ji-whang. The sand contents of subsoil was also negatively correlated with the contents of ash and acid insoluble ash in rhizoma. The clay contents of subsoil was negatively correlated with the catalpol contents, and positively correlated with the contents of fructose, galactose and sucrose in rhizoma, respectively. The clay contents of soil was positively correlated with the ash contents, and negatively correlated with the contents of ethanol extract and water extract in rhizoma, respectively. The organic matter contents of surface soil and subsoil were negatively correlated with the contents of catalpol and extracts (ethanol and water), and positively correlated with the contents of fructose and ash in rhizoma. The total nitrogen contents of surface soil was negatively correlated with the catalpol contents, and positively correlated with the contents of fructose and sucrose in rhizoma. The potassium contents of soil was highly positively correlated with the fructose contents in rhizoma.

• Applied Chemistry for Engineering
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• v.22 no.1
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• pp.21-25
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• 2011

In this study, anatase/brookite hybrid $TiO_2$ was prepared using different acid catalysts and microwave to improve photodegradation of organic pollutants. The methylene blue photodegradation properties of the prepared photocatalysts with different particle/crystal size and brookite fractions were investigated. Surface characteristics and particle sizes of anatase/brookite hybrid $TiO_2$ were evaluated using scanning electron microscopy (SEM) and laser diffraction particle size analyzer, respectively and crystal structures were investigated with X-ray diffraction (XRD). Methylene blue photodegradation properties were evaluated with UV-vis spectrophotometer. Anatase and anatase/brookite hybrid $TiO_2$ had less than 500 nm size of clusters and the average particle size of $6.66{\sim}6.85{\mu}m$, suggesting that types of acid catalysts did not affect the size. XRD of the prepared $TiO_2$ showed that the photocatalysts had anatase/brookite hybrid crystal structure and applying microwave did not change their crystal structure. Photodegradation of methylene blue with the prepared photocatalyst did not increased proportionally to the fraction of brookite and the crystal size and decreased when brookite fraction and the crystal size increased further. Anatase/brookite hybrid $TiO_2$ with brookite fraction of 9.4% and crystal size of 4.53 nm shows the best photodegradation activity of methylene blue.

• Korean Journal of Agricultural Science
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• v.41 no.4
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• pp.379-384
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• 2014

In general, fractal analysis which is based on self-similarity as a basic theory has been mainly used to define the characteristics of complex mathematical figures, however, considering its basic theory, it can be also used to analyze the surface ununiformity of unknown materials. In this study, the soil samples were collected from the reclaimed (remodelled) agricultural fields which mean that the external soil is artificially piled up (mainly up to 1m) on the lands, Naju, Jellanam-do and Gumi, Gyeongsangbuk-do, and the conventional agricultural fields, Anseong, Gyeonggi-do and Hwasoon, Jellanam-do, and compared using fractal dimension analysis on the basis of the results of chemical properties. The score of fractal dimension ($D_0$) for organic matter was lower in Hwasoon (1.46) and Naju (1.58) than Anseong (1.86) and Gumi (1.96), and this trend showed similarly in soil pH. On the basis of the results of chemical properties, fine textured-soils (Hwasoon and Naju) and conventional agricultural fields were chemically uniform compared to coarse textured-soils (Anseong and Gumi) and the reclaimed. Therefore, it is required to develop technical methods for integrated soil management to the reclaimed lands.

• Journal of Environmental Science International
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• v.18 no.5
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• pp.589-594
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• 2009

The goals of this study were conducted to investigate the effects of applying liquid aluminum chloride ($AlCl_3$) to rice hulls on pH and soluble reactive P (SRP). A total of 800 broiler chicks (4 treatments $\times$ 4 replicates $\times$ 50 birds) were housed into 16 floor pens in a single house for 5 weeks. The treatments were divided into 4 groups: control, 100 g of liquid $AlCl_3/kg$ of rice hulls, 200 g of liquid $AlCl_3/kg$ of rice hulls, and 300 g of liquid $AlCl_3/kg$ of rice hulls. Liquid $AlCl_3$ was sprayed on the rice hulls surface at a rate of 100 g, 200 g, and 300 g liquid $AlCl_3$ per kg rice hull. pH values and SRP contents were significantly decreased (P<0.05) with the increased liquid $AlCl_3$ levels in comparison with control. However, no significant differences in SRP contents were observed among all treatments at 3 and 4 weeks. Applying 100 g, 200 g, and 300 g liquid $AlCl_3$ to rice hulls reduced SRP contents by 18, 25, and 52% for 5 weeks, respectively, compared with the controls. In conclusion, these results suggest that using liquid $AlCl_3$ on rice hulls should be promising for reducing water contamination and resulted in a reduction in SRP contents, which reduced pH.

• Korean Journal of Soil Science and Fertilizer
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• v.43 no.4
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• pp.478-483
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• 2010

This study was conducted to investigate the physico-chemical properties of Schizandra chinensis Baillon orchard soils located in Jangsu-gun, Jeollabuk-do. Surface (0 to 10 cm) soils were collected from 200 experimental sites located at Jangsu-eup (53 site), Gyenam-myeon (31), Chunchun-myeon (73), Janggye-myeon (12), Bunyam-myeon (31). The soil texture was mostly loamy sand, and the mean values of degree of soil aggregate and soil porosity were 33.1 and 59.9%, respectively. The pH, EC, total-N, available-P, soil organic matter, and cation exchange capacity of the soils were $5.51{\pm}0.54$, $290{\pm}139{\mu}S\;cm^{-1}$, $946.3{\pm}65.5mg\;kg^{-1}$, $319.6{\pm}29.2mg\;kg^{-1}$, $29.0{\pm}13.9g\;kg^{-1}$ and $4.11{\pm}0.34cmol_c\;kg^{-1}$, respectively. The concentrations of Pb, Cd, Cu and Zn were $3.48{\pm}0.55$, $0.09{\pm}0.04$, $6.90{\pm}0.91$ and $97.7{\pm}42.2mg\;kg^{-1}$, respectively. The presented data can be utilized in better managing Schizandra chinensis Baillon orchard soils in the studied areas.

• Korean Journal of Materials Research
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• v.24 no.1
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• pp.6-12
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• 2014

In the present work, $WO_3$ and $WO_3-TiO_2$ were prepared by the chemical deposition method. Structural variations, surface state and elemental compositions were investigated for preparation of $WO_3-TiO_2$ sonocatalyst. X-ray diffraction (XRD), scanning electron microscopy (SEM), energy dispersive X-ray (EDX) and transmission electron microscopy (TEM) were employed for characterization of these new photocatalysts. A rhodamine B (Rh.B) solution under ultrasonic irradiation was used to determine the catalytic activity. Excellent catalytic degradation of an Rh.B solution was observed using the $WO_3-TiO_2$ composites under ultrasonic irradiation. Sonocatalytic degradation is a novel technology of treating wastewater. During the ultrasonic treatment of aqueous solutions sonoluminescence, cavitaties and "hot spot" occurred, leading to the dissociation of water molecules. In case of a $WO_3$ coupled system, a semiconductor coupled with two components has a beneficial role in improving charge separation and enhancing $TiO_2$ response to ultrasonic radiations. In case of the addition of $WO_3$ as new matter, the excited electrons from the $WO_3$ particles are quickly transferred to $TiO_2$ particle, as the conduction band of $WO_3$ is 0.74 eV which is -0.5 eV more than that of $TiO_2$. This transfer of charge should enhance the oxidation of the adsorbed organic substrate. The result shows that the photocatalytic performance of $TiO_2$ nanoparticles was improved by loading $WO_3$.

• Journal of the Korean Ceramic Society
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• v.52 no.5
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• pp.366-373
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• 2015

Sol-gel binder was prepared by hydrolysis and condensation reaction using boehmite sol and methyltrimethoxysilane as a function of aging-time. The coating slurry was composed of a plate-shape alumina in the sol-gel binder for the EPD process, in which particles dispersed in the slurry were deposited on the electrode under an electric field due to the surface charge. We studied the effects of three parameters: the content of boehmite, the aging time, and the applied voltage, on the physical, thermal, and electrical properties of the hybrid composite films by EPD. The amount of boehmite was 10 ~ 20 wt% and the aging time was 0.5 ~ 72, with a fixed amount of plate-shape alumina of 10 wt%. The condition of applied voltage was 5 ~ 30 V with a distance of 2 cm between the electrode during the EPD process. We confirmed that a structure of hybrid composite films of well-ordered plate alumina was deposited on the substrate when the film was prepared using a sol-gel binder composed of 15 wt% boehmite with 1 hr aging time and EPD at 10 V. The process shows a weight loss of 7% at $500^{\circ}C$ in TGA and a breakdown voltage of 8 kV at $87{\mu}m$.

• Korean Journal of Soil Science and Fertilizer
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• v.35 no.4
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• pp.197-206
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• 2002

Volumetric soil water contents through a soil profile were monitored to identify the effects of tillage systems and soil physico-chemical characteristic on soil water movement from the soil profile. Water content profiles under no tillage (NT) and conventional tillage (CT) practices were compared at two commercial farms in central Illinois from 1992 through 1994, using neutron-scattering techniques in weekly intervals during each growing season. The volumetric water content of surface soil layers was affected more by tillage systems and rainfall amounts, whereas that of the subsoil layers was more strongly affected by soil types. Soil water percolated faster through Saybrook and Catlin soils than through Drummer, Flanagan, and Ipava soils because Saybrook and Catlin soils have lower clay content and water-retention capacity and higher permeability than Drummer, Flanagan, and Ipava soils. Increased soil organic matter (SOM) in Drummer, Flanagan, and Ipava soils would be attributable to the higher soil water retention than other soil types. Soil water contents in the corn root zone were consistently higher under CT plots than under NT plots.

• Journal of the Mineralogical Society of Korea
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• v.20 no.4
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• pp.313-325
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• 2007

In order to have better insights into adsorption of organic molecules on kaolinite surfaces, we performed quantum chemical calculations of interaction between three different model clusters of kaolinite siloxane surfaces and benzyl alcohol, with emphasis on the effect of size and lattice topology of the cluster on the variation of electron density and magnetic shielding tensor. Model cluster 1 is an ideal silicate tetrahedral surface that consists of 7 hexagonal rings, and model cluster 2 is composed of 7 ditrigonal siloxane rings with crystallographically distinct basal oxygen atoms in the cluster, and finally model cluster 3 has both tetrahedral and octahedral layers. The Mulliken charge analysis shows that siloxane surface of model cluster 3 undergoes the largest electron density transfer after the benzyl alcohol adsorption and that of model cluster 1 is apparently larger than that of model cluster 2. The difference of Mulliken charges of basal oxygen atoms before and after the adsorption is positively correlated with hydrogen bond strength. NMR chemical shielding tensor calculation of clusters without benryl alcohol shows that three different basal oxygen atoms (O3, O4, and O5) in model cluster 2 have the isotropic magnetic shielding tensor as $228.2{\pm}3.9,\;228.9{\pm}3.4,\;and\;222.3{\pm}3.0ppm$, respectively. After the adsorption, the difference of isotropic chemical shift varies from 1 to 5.5 ppm fer model cluster 1 and 2 while model cluster 2 apparently shows larger changes in isotropic chemical shift. The chemical shift of oxygen atoms is also positively correlated with electron density transfer. The current results show that the adsorption of benzyl alcohol on the kaolinite siloxane surfaces can largely be dominated by a weak hydrogen bonding and electrostatic force (charge-charge interaction) and demonstrate the importance of the cluster site and the lattice topology of surfaces on the adsorption behavior of the organic molecules on clay surfaces.