Jiwoong Kim

Purification and characterization of arylsulfatase from Sphingomonas sp. AS6330

Arylsulfatase was purified from Sphingomonas sp. AS6330 through ionic exchange, hydrophobic- and gel-chromatographies. The purity increased 12,800-fold with approximately 19.1% yield against cell homogenate. The enzyme was a monomeric protein with apparent molecular weight of 62xa0kDa as determined by sodium dodecylsulfate-polyacrylamide gel electrophoresis, and 41xa0kDa as determined by gel filtration. The enzyme had optimum reaction conditions for hydrolysis of sulfate ester bonds in agar and p-nitrophenyl sulfate (NPS) at pHxa07.0 and 45°C, with a specific activity of 3.93 and 97.2xa0U, respectively. The enzyme showed higher activity towards agar than other sulfated marine polysaccharides such as porphyran, fucoidan and carrageenan. The Km and Vmax of the enzyme for hydrolysis of NPS were 54.9xa0μM and 113xa0mM/min, respectively. With reaction of 200xa0g agar with 100xa0U arylsulfatase for 8xa0h at 45°C, gel strength increased 2.44-fold, and 97.7% of the sulfate in the agar was hydrolyzed.

Atomistic aspects of carrier concentration variation in post-annealed indium tin oxide films

Post-annealing environment-dependent optical and electrical properties of indium tin oxide films grown on glass were examined. X-ray diffraction measurements revealed that all of the films exhibited poly-crystallinity after annealing at 400 °C for 10 min O2, in-air and N2. The optical property measurements yielded >80% transmittances for all the films except for the as-grown and O2-annealed films, even though there were no significant optical band-gap energy differences. In the Hall measurements, all of the films exhibited n-type characteristics. However, the film annealed under the N2 environment showed the best electrical properties (highest carrier concentration and conductivity). The physical origin of electrical property variations due to annealing environment differences was explained by examining the core-level x-ray photoelectron spectra.

Proximal Segment Changes After Bilateral Sagittal Split Ramus Osteotomy in Facial Asymmetry Patients

PURPOSEnTo investigate the 3-dimensional postoperative changes in the proximal segments in patients with facial asymmetry according to the anteroposterior skeletal patterns.nnnMATERIALS AND METHODSnA total of 51 patients with facial asymmetry who had undergone Le Fort I osteotomy and sagittal split ramus osteotomy (SSRO) with rigid fixation were classified according to their anteroposterior skeletal patterns. Cone-beam computed tomography (CBCT) data were obtained before (T0) and 6 months (T1) after surgery. The position, angulation, and distance of the proximal segment were measured from the CBCT superimposition.nnnRESULTSnComparing the T0 and T1 CBCT data, almost no significant differences were found in the condylar head position in any of the groups (P > .05), except for the axial condylar head position on the deviated side in the skeletal Class I group (P < .05) and the sagittal condylar head position on the deviated side in the skeletal Class III group (P < .05). However, the changes in the coronoid process and ramus down varied (P < .05), and these movements were related to changes in the ramal plane. Comparing the deviated and nondeviated sides, significant differences were found only in the skeletal Class I group (P < .05).nnnCONCLUSIONSnThe most influential factors affecting differences between the deviated and nondeviated sides in patients with facial asymmetry after bilateral SSRO could be the direction of the surgical movement of the distal segment of the mandible rather than its extent.

Tuning electromagnetic properties of SrRuO 3 epitaxial thin films via atomic control of cation vacancies

Elemental defect in transition metal oxides is an important and intriguing subject that result in modifications in variety of physical properties including atomic and electronic structure, optical and magnetic properties. Understanding the formation of elemental vacancies and their influence on different physical properties is essential in studying the complex oxide thin films. In this study, we investigated the physical properties of epitaxial SrRuO3 thin films by systematically manipulating cation and/or oxygen vacancies, via changing the oxygen partial pressure (P(O2)) during the pulsed laser epitaxy (PLE) growth. Ru vacancies in the low-P(O2)-grown SrRuO3 thin films induce lattice expansion with the suppression of the ferromagnetic TC down to ~120u2009K. Sr vacancies also disturb the ferromagnetic ordering, even though Sr is not a magnetic element. Our results indicate that both A and B cation vacancies in an ABO3 perovskite can be systematically engineered via PLE, and the structural, electrical, and magnetic properties can be tailored accordingly.

Adsorption and precipitation of cadmium affected by chemical form and addition rate of phosphate in soils having different levels of cadmium

Although a number of studies have examined cadmium (Cd) immobilization by phosphate (P) in soils, determining the exact mechanism of Cd immobilization in various conditions, including P chemical form, P rate, and inherent Cd concentrations in soil has not been examined. The objective of this study was to determine changes in Cd immobilization through adsorption and precipitation in different conditions. Arable soils were spiked with inorganic Cd to give a total Cd concentration of 10, 100, and 1000u202fmg Cd kg-1. K2HPO4 (DPP) and KH2PO4 (MPP) were selected and mixed with the pretreated arable soil at the rates of 0, 800, 1600 and 3200u202fmgu202fP kg-1. In soils with 10 and 100u202fmg Cd kg-1, both P materials similarly increased negative charge of soil and decreased extractable Cd concentration. Using X-ray diffraction (XRD), a diffraction peak revealing the presence of Cd(H2PO4)2 was observed in soil with 1000u202fmg Cd kg-1 and 3200u202fmgu202fP kg-1 soil. In addition, X-ray photoelectron spectroscopy (XPS) analysis and modeling for saturation index for Cd minerals proved that formation of CdCO3 and Cd3(PO4)2 occurred in soil having 1000u202fmg Cd kg-1 and addition of both DPP and MPP. Immobilization of Cd might be attributed to Cd adsorption in soil with relatively low Cd levels (<100u202fmgu202fkg-1). Precipitation of Cd(H2PO4)2, CdCO3, and Cd-phosphate might be a dominant mechanism to immobilize Cd, besides Cd adsorption, in soil with relatively high Cd levels (1000u202fmgu202fkg-1).

How Does Oyster Shell Immobilize Cadmium

The exact mechanism of cadmium (Cd) immobilization by oyster shell (OS) has not been reported. The effect of OS on Cd immobilization and the exact mechanism should be known before applying remediation technology using OS to Cd contaminated soils. Therefore, the objective of this study was to elucidate the mechanism of Cd immobilization by OS. Three grams of OS (<xa00.84xa0mm) was reacted with 30xa0mL of 0–3.56xa0mgxa0Cdxa0L−1 solution at 25xa0°C for 48xa0h. Cadmium adsorption increased with increasing initial concentration of Cd in solution. The X-ray diffraction patterns clearly demonstrated that precipitation of CdCO3 did not take place in suspensions of OS after reacting with up to 3.56xa0molxa0Cdxa0L−1. Interestingly, we found formation of Ca0.67Cd0.33CO3 crystalline in suspension of OS after reacting with maximum initial Cd concentrations. Precipitation and chemisorption might contribute to Cd immobilization together. However, we feel confident that chemisorption is the major mechanism by which Cd immobilization occurs with OS. In conclusion, OS could be an effective bioadsorbent to immobilize Cd through formation of geochemically stable Cd mineral.

Growth of electronically distinct manganite thin films by modulating cation stoichiometry

Nd1-xSrxMnO3 is a well-known manganite due to close connection among structure, transport, magnetism, and chemistry. Thus, it would be an ideal system to study the modification of physical properties by external stimuli including control of stoichiometry in growth. In this work, we show that an abrupt change of electronic and magnetic properties can be achieved by a subtle change of oxygen partial pressure in pulsed laser deposition. Interestingly, the pressure indeed modulates cation stoichiometry. We clearly observed that the films grown at 140 mTorr and higher showed clear insulator to metal transition and stronger magnetism, commonly found in less hole doping, while the films grown at 130 mTorr and lower showed insulating behavior and weak magnetism. From soft x-ray spectroscopic methods, we clearly observed the compositional difference in those thin films. This result is further supported by scattering of lighter elements in high oxygen partial pressure but not by anion deficiency in growth.Nd1-xSrxMnO3 is a well-known manganite due to close connection among structure, transport, magnetism, and chemistry. Thus, it would be an ideal system to study the modification of physical properties by external stimuli including control of stoichiometry in growth. In this work, we show that an abrupt change of electronic and magnetic properties can be achieved by a subtle change of oxygen partial pressure in pulsed laser deposition. Interestingly, the pressure indeed modulates cation stoichiometry. We clearly observed that the films grown at 140 mTorr and higher showed clear insulator to metal transition and stronger magnetism, commonly found in less hole doping, while the films grown at 130 mTorr and lower showed insulating behavior and weak magnetism. From soft x-ray spectroscopic methods, we clearly observed the compositional difference in those thin films. This result is further supported by scattering of lighter elements in high oxygen partial pressure but not by anion deficiency in growth.