• Journal of Microbiology and Biotechnology
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• v.18 no.8
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• pp.1386-1392
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• 2008

A gene (sll0158) putatively encoding a glycogen branching enzyme (GBE, E.C. 2.4.1.18) was cloned from Synechocystis sp. PCC6803, and the recombinant protein expressed and characterized. The PCR-amplified putative GBE gene was ligated into a pET-21a plasmid vector harboring a T7 promoter, and the recombinant DNA transformed into a host cell, E. coli BL21(DE3). The IPTG-induced enzymes were then extracted and purified using Ni-NTA affinity chromatography. The putative GBE gene was found to be composed of 2,310 nucleotides and encoded 770 amino acids, corresponding to approx. 90.7 kDa, as confirmed by SDS-PAGE and MALDI-TOF-MS analyses. The optimal conditions for GBE activity were investigated by measuring the absorbance change in iodine affinity, and shown to be pH 8.0 and $30^{\circ}C$ in a 50 mM glycine-NaOH buffer. The action pattern of the GBE on amylose, an $\alpha$-(1,4)-linked linear glucan, was analyzed using high-performance anion-exchange chromatography (HPAEC) after isoamylolysis. As a result, the GBE displayed $\alpha$-glucosyl transferring activity by cleaving the $\alpha$-(1,4)-linkages and transferring the cleaved maltoglycosyl moiety to form new $\alpha$-(1,6)-branch linkages. A time-course study of the GBE reaction was carried out with biosynthetic amylose (BSAM; $M_p{\cong}$8,000), and the changes in the branch-chain length distribution were evaluated. When increasing the reaction time up to 48 h, the weight- and number-average DP ($DP_w$ and $DP_n$) decreased from 19.6 to 8.7 and from 17.6 to 7.8, respectively. The molecular size ($M_p$, peak $M_w{\cong}2.45-2.75{\times}10^5$) of the GBE-reacted product from BSAM reached the size of amylose (AM) in botanical starch, yet the product was highly soluble and stable in water, unlike AM molecules. Thus, GBE-generated products can provide new food and non-food applications, owing to their unique physical properties.

• Applied Biological Chemistry
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• v.28 no.1
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• pp.19-27
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• 1985

The physicochemical properties of starch isolated from Yullmoo (Coix lachrymajobi var. mayuen stapf.) and Yeomjoo (Coix lachryma-jobi L.) were investigated. The average diameters of starch granules of Yullmoo and Yeomjoo were 12.0 microns, both of all, and the shape of these starch granules were hexagon, octagon and round. X-ray diffraction patterns of two samples were A-types and amylose contents of Yullmoo and Yeomjoo starch were 0% and 23%, respectively, iodine affinities of these were 0.08% and 4.2%, respectively, blue values and alkali numbers of these were 0.13 and 0.43, 2.4 and 7.2, and raising power of these were 280 and 20, respectively. Yullmoo starch had higher swelling power than Yeomjoo starch. The increase in optical transmittance of 0.1% suspensions of Yullmoo and Yeomjoo starches occurred at $60^{\circ}C$ and continued up to $75^{\circ}C$ for Yullmoo, $85^{\circ}C$ for Yeomjoo. Amylogram data on 5% of Yullmoo and Yeomjoo starch suspensions showed that gelatinization temperatures and maximum peak heights of Yullmoo and Yeomjoo were $68.5^{\circ}C\;and\;78^{\circ}C$, 920 and 310 B.U., respectiyely. Intrinsic viscosities of Yullmoo and Yeomjoo starches were 1.49 and 1.77, respectively, and interaction coefficients of the two starches were 0.57 and 0.56, respectively The extent of retrogradation determined at $2^{\circ}C$ showed that retrogradation occurred slowly with Yullmoo starch paste tut little with Yullmoo.

• Membrane Journal
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• v.21 no.3
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• pp.213-221
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• 2011

Using poly(ethylene oxide) (PEO) as a polymer host, poly(ethylene glycol) (PEG) as a plasticizer, potassium iodide and iodine as sources of $I^-/I_3^-$, polymer electrolyte membranes were prepared. Based on the polymer electrolytes, solid-state dye-sensitized solar cell (DSSC)s were fabricated. The content of PEG in the electrolyte was controlled to be 95%. The mole number of KI per 1 mole of EO ([KI]/[EO] ratio) in the electrolyte was changed to be 0.022, 0.044, 0.066 and 0.088. The electrolyte membrane showed wax phase in ambient temperature. The ionic conductivity increased with increasing KI content to reach the maximum value at which [KI]/[EO] ratio is 0.066. After the maximum value, the ionic conductivity decreased with increasing KI content. In the case of DSSC, the Voc decreased continuously with increasing KI content in the polymeric electrolyte membrane. The $J_{SC}$ increased with increasing KI content to show maximum value at which [KI]/[EO] ratio is 0.044. In the higher KI content region, $J_{SC}$ value decreased with increasing KI content.

• Resources Recycling
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• v.17 no.5
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• pp.66-75
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• 2008

Using a pinus koraiensis and pinus rigida which are normally being discarded in South Korea, the optimal condition of producing charcoals has been studied to develop activated carbons which can be recycled as a higher value-added product. A study on manufacture of activated carbons from a discarded timber consists of two processes, the production process of charcoals from a discarded timber by low temperature pyrolysis process and the production process of activated carbons from the charcoals by chemical activation reaction. This study deals with the production process of charcoals from a discarded timber by low temperature pyrolysis process. As a results of experiment, it was investigated that charcoals produced through drying at $150^{\circ}C$ for 6hr and pyrolysis process at $500^{\circ}C$ for 1hr had the highest values in physical properties such as iodine number and BET surface area. Furthermore, through observing SEM images, the maximum development of porosity had been founded in this condition. It was confirmed that values of physical properties on using a pinus koraiensis are superior to the ones when using a pinus rigida. When charcoals were produced from a pinus koraiensis in this condition, BET surface area was approx. $640m^2/g$.

• International Journal of Oral Biology
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• v.42 no.4
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• pp.155-161
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• 2017

Teeth and bones are highly mineralized tissues containing inorganic minerals such as calcium phosphate, and a growing number of evidences show that their mineral content is associated with many diseases. Although the quantification of mineral contents by micro-computed tomography(micro- CT) has been used in diagnosis and evaluation for treating bone diseases, its application for teeth diseases has not been well established. In this study, we attempted to estimate a usefulness of a high-resolution micro-CT in analysis of human teeth. The teeth were scanned by using the Skyscan 1172 micro-CT. In order to measure tooth mineral content, beam hardening effect of the machine was corrected with a radiopaque iodine-containing substance, iodoacetamide. Under the maximum resolution of $6.6{\mu}m$, X-ray densities in teeth and hydroxyapatite standards were obtained with Hounsfield unit (HU), and they were then converted to an absolute mineral concentration by a CT Analyzer software. In enamel layer of cusp area, the mean mineral concentration was about $2.14mg/mm^3$ and there was a constant mineral concentration gradient from the enamel surface to the dentinoenamel junction. In the dentin of middle 1/3 of tooth, the mean mineral concentration was approximately $1.27mg/mm^3$ and there was a constant mineral concentration gradient from the outer of root to the pulp side, ranging from 1.3 to $1.06mg/mm^3$. In decay region of dentin, the mineral content was gradually decreased from the intact inner side to the decayed surface. These results suggest that high-resolution micro-CT can be as a useful tool for non-invasive measurement of mineral concentration in teeth.

• Korean Journal of Food Science and Technology
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• v.32 no.6
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• pp.1213-1220
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• 2000

The mutagenicity of the thermally oxidized soybean oils was investigated. Each oil sample was taken after 0, 8, 16, 24, 32, 40, and 48 hours of heating at a temperature of $180{\pm}3^{\circ}C$, and was used to study the changes of peroxide value(POV), acid value(AV), iodine value(IV), conjugated dienoic acid content(CDA content, %), and fatty acid composition. Another set of samples was fractionated into non-oxidized and oxidized fractions by column chromatography using silica gel. The mutagenicity of the samples taken from the thermally oxidized oils as well as the non-oxidized and oxidized fractions was investigated with the Ames test. Bacterial tester strains used in the present study were the histidine auxotrophic strains of S. typhimurium TA100, TA1535 and TA 102 for the detection of base pair, and TA98 and TA1537 for frame shift mutations. Each set of samples was dissolved in tetrahydrofuran and tested at doses ranging from 0.05 to 5 mg/plate. The oxidized fractions increased significantly the number of $His^+$ revertant colonies of TA100, TA1537 and TA102, thereby showed mutagenic activity on these strains. However none of the oil samples taken within the 48 hours oxidation period showed any mutagenic activity with and without metabolic activation.

• Journal of the Korean Society of Radiology
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• v.15 no.5
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• pp.575-584
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• 2021

The aim of this study was to achieve optimal portal phase while reducing contrast medium by applying weight-based dose protocol compared to standard fixed dose protocol to performing of pediatric abdominal CT examination. Discovery 750HD (General Electric Medical Systems, Milwaukee, USA) was used, and a total of 167 children consisting of 85 men and 82 women under the age of 18 were studied. The group in which the 300 mgI/ml(Xenetix, Guerbet, France) contrast medium was fixedly injected at twice body weight and the group injected with physiological saline while gradually decreasing the injection amount by 10% while applying the weight-based protocol were distinguished. Also, the CT number and SNR of abdominal organs were compared and evaluated while changing the scan delay time. Subjective image quality of enhancement and beam-hardening artifacts of around the heart was assessed with five-point criterion. The group adapted weight-based protocol with 20% reduction in contrast medium was most similar in contrast enhancement in the group with fixed injection at twice body weight. Furthermore, the group with a delay time of 20% had the highest contrast enhancement effect, and the difference in CT attenuation coefficient from the group scanned immediately after injection of the contrast media. Therefore, the appropriate delay time after injection of the contrast agent increased the contrast enhancement of the parenchymal organ. In addition, the weight-based injection protocol with normal saline reduced artifacts around the heart, and the effect of contrast enhancement could be maintained. In conclusion, it is possible to reduce dosage of contrast media through the application of weight-based injection protocols and appropriate latency, and to characterize optimal portal phase imaging on pediatric abdominal CT.

• Clean Technology
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• v.29 no.4
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• pp.272-278
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• 2023

There is a lot of interest in methods for pollutants using adsorption, and recent research is being conducted to show that biochar can be used to remove organic and inorganic pollutants. In particular, wood waste as waste biomass requires a biomass recycling method, and a method to increase the adsorption capacity of biochar produced using wood waste is needed. Biochar is created by Hydrothermal carbonization (HTC) using, which uses low temperature and high pressure, has low energy consumption and does not require moisture removal pretreatment, and biochar is created through chemical activation using KOH, NaOH, and ZnCl₂ chemicals. The adsorption characteristics of biochar were determined by analyzing iodine adsorptivity, specific surface area, pore diameter, pore volume, pore distribution, and SEM according to the activation. The results of analyzing the selecting biochar by activating the biochar produced at HTC 300℃, 4 hr by KOH, NaOH, and ZnCl₂ chemicals, the specific surface area was 774~1.387 m²/g, showing a high specific surface area similar to activated carbon, and it was confirmed that micropores with an average pore diameter in the range of 21~24 Å were formed. As a result of SEM observation, the surface was uniform with a certain shape depending on activation. It was confirmed that one pore was developed and the number of pores increased.

• Korean Journal of Materials Research
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• v.34 no.1
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• pp.1-11
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• 2024

This research investigated the preparation of activated carbon derived from Krabok (Irvingia malayana) seed shells to improve the quality of crude glycerol obtained during biodiesel production. The activated carbon was prepared using a dry chemical activation method with NaOH, utilizing an innovative biomass incinerator. The results revealed that the resulting KC/AC-two-step exhibited favorable physicochemical adsorption properties, with a high surface area of 758.72 m²/g and an iodine number of 611.10 mg/g. These values meet the criteria of the industrial product standard for activated carbon No. TIS 900-2004, as specified by the Ministry of Industry in Thailand. Additionally, the adsorption efficiency for methylene blue reached an impressive 99.35 %. This developed activated carbon was then used to improve the quality of crude glycerol obtained from biodiesel production. The experimental results showed that the KC/AC-two-step increased the purity of crude glycerol to 73.61 %. In comparison, commercially available activated carbon (C/AC) resulted in a higher crude glycerol purity of 81.19 %, as analyzed by the GC technique. Additionally, the metal content (Zn, Cu, Fe, Pb, Cd, and Na) in purified glycerol using KC/AC-two-step was below the standards for heavy metals permitted in food and cosmeceuticals by the Food and Drug Administration of Thailand and the European Committee for Food Contact Materials and Articles. As a result, it can be inferred that Krabok seed shells have favorable properties for producing activated carbon suitable as an adsorbent to enhance crude glycerol purity. Furthermore, the improved crude glycerol from this research has potential for various industrial applications.

• Journal of the Korean Society of Radiology
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• v.13 no.6
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• pp.879-887
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• 2019

The purpose of this study is to establish a physiological injection protocol according to body weight, in order to minimize amount of contrast medium and optimize contrast enhancement in pediatric patients performing thoracic CT examinations. The 80 pediatric patients under the age of 10 were studied. Intravenous contrast material containing 300 mgI/ml was used. The group A injected with a capacity of 1.5 times its weight, and groups B, C and D added 5 to 15 ml of normal saline with a 10% decrease in each. The physiologic model which can be calculated by weight about amount of injection of contrast medium and normal saline, flow rate and delay time were applied. To assess image quality, measured average HU value and SNR of superior vena cava, pulmonary artery, ascending and descending aorta, right and left atrium, right and left ventricle. CT numbers of subclavian vein and superior vena cava were compared to identify the effects of reducing artifacts due to normal saline. Comparing SNR according to the contrast medium injection protocol, significant differences were found in superior vena cava and pulmonary artery, descending aorta, right and left ventricle, and CT numbers showed significant differences in all organs. In particular, B group with a 10% decrease in contrast medium and an additional injection of saline showed a low degree of contrast enhancement in groups with a decrease of more than 20%. In addition, the group injected with normal saline greatly reduced contrast enhancement of subclavian vein and superior vena cava, and the beam hardening artifact by contrast medium was significantly attenuated. In conclusion, the application of physiological protocol for injection of contrast medium in pediatric thoracic CT examinations was able to reduce artifacts by contrast medium, prevent unnecessary use of contrast medium and improve the effect of contrast enhancement.