• Applied Chemistry for Engineering
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• v.10 no.1
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• pp.51-57
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• 1999

Adsorption characteristics of Ni(II), Co(II) and Ag(I) ions on the Amberite IRN 77 cation exchange resin have been studied to suggest the guide-line for the optimum operation of demineralization process in primary coolant system during the shut-down period of pressurized water reactor(PWR). The adsorption mechanism of each metal ion, Ni(II), Co(II) or Ag(I) ion, on a cation exchange resin was well coincided with Langmuir isotherm. The adsorption and treatment capacities of $H^+$-form resin were higher than those of $Li^+$-form resin. In the continuous ion exchange process for the solution of multi-component system, the selectivity of the resin was in increasing order of Ni(II)${\approx}$Co(II)>Ag(I). In addition, the increase of the flow rate decreased the treatment capacity of the resin as well as the slope of the breakthrough curve.

• Food Science of Animal Resources
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• v.38 no.5
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• pp.1080-1091
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• 2018

The eggshell, which is a complex and highly ordered structure, is very important factor for food safety and egg marketing. This study investigated the changes in eggshell structure and shell components in relationship to hen age. For this study, we examined the histological change of the endometrium of the 30-, 60-, and 72-wk-old commercial layers, and analyzed the ultrastructure and ionic composition of their eggshells. The results showed that histological deformation, fibrosis, atrophy and elimination of micro-villi in the uterus endometrium were found through microscopic observation that was associated with increasing hen age. Concentration of blood-ion components such as $Ca^{2+}$, $Na^+$, $K^+$, and $Cl^-$ ions did not change with age. Along with the results from the ultrastructure analysis of the eggshell, the palisade layer ratio and the density of mammillary knobs were significantly decreased in older hens. In addition, the type B mammillary knobs were frequently observed with increasing hen age. In the mineral element assay from the eggshell, $Ca^{2+}$, $S^{2-}$, and $Co^{2+}$ significantly decreased with increasing hen age, whereas $Na^+$, $K^+$, and $V^{2+}$ significantly increased. Therefore, the damages of endometrial tissue inhibit the processes of ion transmission and the crystallization of eggshell formation, resulting in a large and non-uniform mammillary knob formation. This means the conditions of endometrial cells affect the formation of the eggshell structure. In conclusion, hen aging causes the weakness of the eggshell and degrades the eggshell quality.

• Korean Journal of Materials Research
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• v.13 no.1
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• pp.43-47
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• 2003

As and BF$_2$dopants are implanted for the formation of source/drain with dose of 1${\times}$10$^{15}$ ions/$\textrm{cm}^2$∼5${\times}$10$^{15}$ ions/$\textrm{cm}^2$ then formed cobalt disilicide with Co/Ti deposition and doubly rapid thermal annealing. Appropriate ion implantation and cobalt salicide process are employed to meet the sub-0.13 $\mu\textrm{m}$ CMOS devices. We investigated the process results of sheet resistance, dopant redistribution, and surface-interface microstructure with a four-point probe, a secondary ion mass spectroscope(SIMS), a scanning probe microscope (SPM), and a cross sectional transmission electron microscope(TEM), respectively. Sheet resistance increased to 8%∼12% as dose increased in $CoSi_2$$n^{＋}$ and $CoSi_2$$p^{V}$ , while sheet resistance uniformity showed very little variation. SIMS depth profiling revealed that the diffusion of As and B was enhanced as dose increased in $CoSi_2$$n^{＋}$ and $CoSi_2$$p^{＋}$ . The surface roughness of root mean square(RMS) values measured by a SPM decreased as dose increased in $CoSi_2$$n^{＋}$ , while little variation was observed in $CoSi_2$$p^{＋}$ . Cross sectional TEM images showed that the spikes of 30 nm∼50 nm-depth were formed at the interfaces of $CoSi_2$$n^{＋}$ / and $CoSi_2$/$p^{＋}$, which indicate the possible leakage current source. Our result implied that Co/Ti cobalt salicide was compatible with high dose sub-0.13$\mu\textrm{m}$ process.

• Journal of the Institute of Electronics Engineers of Korea SD
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• v.41 no.5
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• pp.37-42
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• 2004

Shallow $p^{＋}$-n junctions were formed by preamorphization, low-energy ion implantation and dual-step annealing processes. Germanium ions were implanted into silicon substrates for preamorphization. The dopant implantation was performed into the preamorphized and non-preamorphized substrates using B $F_2$2 ions. Rapid thermal anneal (RTA) and furnace anneal (FA) were employed for dopant activation and damage removal. Samples were annealed by one of the following four methods; RTA(75$0^{\circ}C$/10s)＋Ft FA＋RTA(75$0^{\circ}C$/10s), RTA(100$0^{\circ}C$/10s)＋FA, FA＋The Ge Preamorphized sample exhibited a shallower junction depth than the non-preamorphized sample. When the employed RTA temperature was 100$0^{\circ}C$, FA＋RTA annealing sequence exhibited better junction characteristics than RTA＋FA thermal cycle from the viewpoint of junction depth, sheet resistance, $R_{s}$$.$ $x_{j}$, and leakage current.t.

• Journal of Sensor Science and Technology
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• v.1 no.1
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• pp.85-92
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• 1992

A new potassium sensitive field effect transistor modified with 4'-aminobenzo-15-crown-5 was prepared and its response characteristics were evaluated. The response slope of $K^{+}-ISFET$ for pH was 30.0 mV/decade and the response time was mere than 3 minutes. And the response slope and time of the $K^{+}-ISFET$ for potassium ion as $19.5{\pm}0.2{\;}mV/decade$ and about 3 minutes, respectively. The linear response range of the sensor for potassium ion was $2.0{\times}10^{-4}{\sim}1.0{\times}10^{-2}M$. The selectivity coefficients of the $K^{+}-ISFET$ for the alkali and alkaline earth metal ions were also evaluated. Sodium, ammonium and calcium ions exhibited relatively significant interference. The long term stability of the sensor was remarkably improved and it could be used for more than 50 days.

• Natural Product Sciences
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• v.17 no.2
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• pp.147-159
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• 2011

A high-performance liquid chromatography-electrospray ionization-tandem mass spectrometric method was developed to determine simultaneously eight marker constituents of Forsythiae fructus, and subsequently applied it to classify its two botanical origins. The marker compounds of Forsythia suspensa were phillyrin, pinoresinol, phillygenin, lariciresinol and forsythiaside; those of F.viridissima were arctiin, arctigenin and matairesinol. Separation of the eight analytes was achieved on a phenyl-hexyl column (150${\times}$2.0 mm i.d., 3 ${\mu}M$) using gradient elution with the mobile phase: (A) 10% acetonitrile in 0.5% acetic acid, (B) 40% aqueous acetonitrile. A few fragment ions specific to the types of lignans, among the product ions generated by collisonally induced dissociation (CID) of molecular ion clusters, such as [M-H]$^-$ or [M+OAc]$^-$ were used not only for fingerprinting analysis but for the quantification of each epimer by using multiple-reaction monitoring mode. It was shown good linearity ($r^2{\geq}$ 0.9998) over the wide range of all analytes; intra- and inter-day precisions (RSD, %) were within 9.14% and the accuracy ranged from 84.3 to 115.1%. The analytical results of 40 drug samples, combined with multivariate statistical analyses - principal component analysis (PCA) and hierarchical cluster analysis (HCA) - clearly demonstrated the classification of the test samples according to their botanical origins. This method would provide a practical strategy for assessing the authenticity or quality of the herbal drug.

• Journal of Powder Materials
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• v.27 no.5
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• pp.381-387
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• 2020

In this work, TiO₂ 3D nanostructures (TF30) were prepared via a facile wet chemical process using ammonium hexafluorotitanate. The synthesized 3D TiO₂ nanostructures exhibited well-defined crystalline and hierarchical structures assembled from TiO₂ nanorods with different thicknesses and diameters, which comprised numerous small beads. Moreover, the maximum specific surface area of TiO₂ 3D nanostructures was observed to be 191 ㎡g^-1, with concentration of F ions on the surface being 2 at%. The TiO₂ 3D nanostructures were tested as photocatalysts under UV irradiation using Rhodamine B solution in order to determine their photocatalytic performance. The TiO₂ 3D nanostructures showed a higher photocatalytic activity than that of the other TiO₂ samples, which was likely associated with the combined effects of a high crystallinity, unique features of the hierarchical structure, a high specific surface area, and the advantage of adsorbing F ions.

• 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.

• Journal of Microbiology and Biotechnology
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• v.22 no.3
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• pp.331-338
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• 2012

A novel gene coding for an endo-${\beta}$-1,4-mannanase (manA) from Bacillus subtilis strain G1 was cloned and overexpressed in P. pastoris GS115, and the enzyme was purified and characterized. The manA gene consisted of an open reading frame of 1,092 nucleotides, encoding a 364-aa protein, with a predicted molecular mass of 41 kDa. The ${\beta}$-mannanase showed an identity of 90.2-92.9% ${\leq}95%$) with the corresponding amino acid sequences from B. subtilis strains deposited in GenBank. The purified ${\beta}$-mannanase was a monomeric protein on SDS-PAGE with a specific activity of 2,718 U/mg and identified by MALDI-TOF mass spectrometry. The recombinant ${\beta}$-mannanase had an optimum temperature of $45^{\circ}C$ and optimum pH of 6.5. The enzyme was stable at temperatures up to $50^{\circ}C$ (for 8 h) and in the pH range of 5-9. EDTA and most tested metal ions showed a slightly to an obviously inhibitory effect on enzyme activity, whereas metal ions ($Hg^{2+}$, $Pb^{2+}$, and $Co^{2+}$) substantially inhibited the recombinant ${\beta}$-mannanase. The chemical additives including detergents (Triton X-100, Tween 20, and SDS) and organic solvents (methanol, ethanol, n-butanol, and acetone) decreased the enzyme activity, and especially no enzyme activity was observed by addition of SDS at the concentrations of 0.25-1.0% (w/v) or n-butanol at the concentrations of 20-30% (v/v). These results suggested that the ${\beta}$-mannanase expressed in P. pastoris could potentially be used as an additive in the feed for monogastric animals.

• Journal of the Korean Ceramic Society
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• v.37 no.8
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• pp.781-786
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• 2000

An Er-doped sulfide fiber was drawn, and its spectroscopic properties were analyzed. Compositions of a 1000 ppmwt Er3+-doped core and an undoped clad were Ge30-Ga1-Asg-S61 and Ge30-As8-S62, in at.%, respectively. Refractive index of the core composition was approximately 0.01 high than that of the clad. In order to enhance the mechanical stability as well as to prevent infiltration of impurity ions such as OH-, an UV-curable polymer was used for the coating. The optical loss of a fiber formed directly from a polymer coated core rod without cladding was ∼15 dB/m at 1.06$\mu\textrm{m}$. In the case of a fiber with core/clad structure, the optical loss was so high that the stimulated emission of erbium fluorescence was not evident. It is believed that presence of inhomogeneous core/clad interface and crystalline aggregates precipitated in the clad region were responsible for the high optical loss. On the other hand, fluorescence characteristics of Er3+ embedded in the core region were more or loss deteriorate compared to fiber preform, which is attributed to the redistribution of the Er ions along with the partial crystallization of the core glass during the fiberization process.