• Analytical Science and Technology
• /
• v.24 no.2
• /
• pp.61-68
• /
• 2011

Ni-coated alumina was prepared by sonochemical method. To increase an efficiency of Ni coating on alumina, amorphous alumina was prepared by sol-gel method and Ni was coated to fine particles of alumina. Ni-coated alumina was prepared from various calcination temperatures ($500^{\circ}C$, $1,000^{\circ}C$), concentrations of Ni solution (0.01 M~0.2 M) and sonochemical reaction times (30 min, 2h). The prepared fine particles were characterized by X-Ray Diffractometer (XRD), Scanning Electron Microscope (SEM), Inductively Coupled Plasma Atomic Emission Spectroscopy (ICP-AES), and Particle Size Analyzer (PSA). The coating amount of Ni increased, as Ni concentration and ultrasonication time increased. The maximum amount of Ni was coated to fine particles of alumina, when Ni-coated alumina was prepared with 0.1 M concentration of Ni solution for 2 h of sonication time at $1000^{\circ}C$ of calcination temperature. The average particle size was in the range of 835.9 to 986.7 nm.

• Journal of the Korean Ceramic Society
• /
• v.33 no.8
• /
• pp.915-920
• /
• 1996

Fine mullite precursor was prepared by colloidal sol-gel processes. Aluminum isopropoxide $[Al(i-OC_3H_7)_3]$ as a starting material of $Al_2O_3$ and silicic acid extracted by THF from sodium silicate as a starting material of $SiO_2$ were used. Sodium silicate was first acidified by dilute sulfuric acid to form silicic acid. ; followed by extraction using THF, Mullite precursor was synthesized by sol-gel processes from aluminum isopropoxide and sillicic acid considering the degree of extraction of Si and the removal efficiency of Na. The impurity content of silicic acid extracted by THF was below 0.04% Synthetic mullite precursor consisted of $3Al_2O_3{\cdot}2SiO_2$ and showd spherical particles of $0.05{\mu}m$ diameter and below 0.462% of impurites. The mullite precursor was characterized by EDS, XRD, TG/DSC SEM, FT-IR spectroscopy ICP and TEM.

• Journal of the Korean Institute of Telematics and Electronics D
• /
• v.36D no.4
• /
• pp.56-62
• /
• 1999

In this study, (Ba, Sr)$TiO_3$ thin films were etched with $Cl_2$/Ar gas mixing ratio in an inductively coupled plasma (ICP) by varying the etching parameter such as rf power, dc bias voltage, and chamber pressure. The etch rate was 56 nm/min under $Cl_2$/($Cl_2$+Ar) gas mixing ratio of 0.2, rf power of 600 W, dc bias voltage of 250 V, and chamber pressure of 5 mTorr. At this time, the selectivity of BST to Pt, $SiO_2$ was respectively 0.52, 0.43. The surface reaction of the etched (Ba, Sr)$TiO_3$ thin films was investigated with X-ray photoelectron spectroscopy (XPS). Ba is removed by chemical reaction between Sr and Cl to remove Sr. Ti is removed by chemical reaction such as $TiCl_4$ with ease. The results of secondary ion mass spectrometer (SIMS) analysis compared with the results of XPS analysis and the results were the same.

• Journal of the Korean Applied Science and Technology
• /
• v.30 no.2
• /
• pp.225-232
• /
• 2013

Omija component was known to possess natural odor, taste, color, and various general characteristics. Omija extraction was extracted using ethanol as a solvent. Omija extract showed a red-purple color of some viscous liquid state. Some conclusions from natural Omija extract were obtained as follow. The result of antimicrobial experiment to add Omija extract, the number of microbial population showed negative reaction from 3 days after it cultivated. This phenomenon could confirm that Omija component affected to antimicrobial effect. The result of dyeing experiment to add Omija extract, fiber dyeing effect showed with some ivory color after dyed to cotton and silk. Also, this phenomenon could confirm that Omija component affected to natural dyeing effect from observated dye state with biological microscope(BM). The result of instrumental analysis, inorganic components of K(109.60ppm), Na(3.500ppm), Ca(1.205ppm), Mg(0.900ppm), Li(0.350ppm), Si(0.380ppm), Cu(0.250ppm), Fe(0.125ppm), Zn(0.090ppm), etcs from Omija were ascertained with ICP/OES, and organic components of benzene(10.808), borny lacetate(11.289), phenol(14.183), ${\beta}$-terpinene(15.840), ${\alpha}$-terpinolene(17.616) etcs from Omija were ascertained with GC/MSD.

• Journal of the Korean institute of surface engineering
• /
• v.41 no.6
• /
• pp.269-273
• /
• 2008

The etch of $(Na_{0.5}K_{0.5})NbO_3$ (NKN) thin film was performed in $BCl_3/Cl_2/Ar$ inductively coupled plasma. It was found that the 1sccm addition $BCl_3$ (5%) into $Cl_2/Ar$ plasma caused a non-monotonic behavior of the NKN etch rate. The maximum etch rate of NKN was 95.3 nm/min at $BCl_3$ (1 sccm)/$Cl_2$ (16 sccm)/Ar (4 sccm), 800 W ICP power, 1 Pa pressure and 400 W bias power. The NKN etch rate shows a monotonic behavior a s the bias power increases. The analysis of the narrow scan spectra of XPS for both a s-deposited and etched NKN films allowed one to assume ion assisted etch mechanism. The most probable reason for the maximum etch rate can be defined as a concurrence of chemical and physical etch pathways.

• Journal of the Korean Chemical Society
• /
• v.38 no.9
• /
• pp.660-666
• /
• 1994

The effects of temperature and flow rate of eluent on the separation of adjacent lighter lanthanide pairs (La : Ce, Ce : Pr, Pr: Nd) have been studied with displacement chromatography. Two serial columns packed with Amberlite 120 cation exchange resin are used for loading and separation. The retaining ion is $H^+$ ion and the eluent is 0.012M and 0.015M of EDTA solution. The columns and the eluent are maintained at the temperature of 90$^{\circ}C$ and pressurized to reduce vaporizing in the ion-exchange resin column. The eluated solution is analyzed directly with ICP-AES. The separation factors of the lanthanide pairs, La: Ce, Ce :Pr, and Pr: Nd, are 4.6, 2.8, and 1.9, respectively and are higher than that from theoretical calculation at 25$^{\circ}C$. When the flow rate is reduced from 2.5 ml/min to 1.5 ml/min, the HETP is reduced from 1.60 cm to 0.88 cm. The separation efficency can be improved at lower flow rate of eluent and higher operating temperature. The recoveries of pure lanthanides than 99.9% are 49∼77% from this separation.

• Applied Chemistry for Engineering
• /
• v.10 no.4
• /
• pp.568-575
• /
• 1999

Two different digestion procedures for the simultaneous determination of major and platinum-group element(PGE) in spent automobile catalysts containing PGE and silicates by inductively coupled plasma atomic emission spectrometry(ICP-AES) are compared. Combinations of mixed aids using HF, $HNO_3$, HCl, $HClO_4$, $H_2O_2$, and $H_3BO_3$ are utilized for the hot plate dissolution method and the closed-vessel microwave digestion method, The latter method has been shown to be relatively superior in terms of recovery, analysis time, and amount of aqua regia (3 parts HCl + part $HNO_3$ required to dissolve PGE in comparison with conventional open vessel hot-plate dissolution. The best results were drawn from the following conditions: In closed Teflon PFA vessels under microwave heating with temperature/pressure regulation, a 0.25 g portion of sample was digested in 2 mL of HF, 2 mL of $HNO_3$ and 6mL of HCl under the pressure of 200 psi(13.79 bar) at $180^{\circ}C$ for 1hr, followed by a second digestion stage with 16 mL of 5%(w/v) boric acid under the pressure of 20 psi(1.38 bar) at $100^{\circ}C$ for 10 min. After the microwave heating, the sample was post-treated with 10 mL of aqua regia twice by hot-plate heating. This condition gives the PGE recovery within 85~110% and the relative standard deviations within 2%. The method developed can therefore be regarded as an alternative method for routine analysis of spent automobile catalysts.

• Journal of Korean Neurosurgical Society
• /
• v.30 no.sup2
• /
• pp.309-315
• /
• 2001

The term slit ventricle syndrome(SVS) refers to an episodic occurrence of headache, vomiting, and possibly some degree of impaired consciousness in shunted hydrocephalic children in whom slit-like ventricles are seen on CT scan or MRI. Authors present 6 cases with SVS who were treated at our institute for last 10 years. From 1986 to 1996, 821 patients underwent shunt surgery for hydrocephalus. The etiology of hydrocephalus included brain tumor(140 patients), post-hemorrhagic(62 patients), idiopathic normotensive hydrocephalus(64 patients), post-meningitic( 58 patients), post-traumatic(54 patients), congenital(48 patients), neurocysticercosis(31 patients), and unknown etiology(364 patients). During the mean follow-up duration of 68 months, 232 shunt revisions were performed by a revision rate of 1.28 per patient. The incidence of SVS was 0.7%(6 patients). Most of them have been operated on in infancy. Time interval from the first operation to the development of slit-ventricle syndrome ranged from 4 to 8 years, the mean was 6 years. Shuntogram showed patent shunt in all patients. Two patients with less severe clinical symptoms improved with conservative treatment. These patients were not measured ICP because of good hospital course. One patient showed high ICP and needed only revision with same pressure valve as previous shunt. Low ICP was noted in 3 patients. Pressure augmentation using an anti-siphon device(ASD) or upgrading valve system were necessary in these patients. The authors stress that determining type of SVS is the first step in treatment planning and that the best treatment is a strategy aimed at resolving the specific type of SVS responsible for the symptoms.

• Journal of the Korean Chemical Society
• /
• v.63 no.5
• /
• pp.335-341
• /
• 2019

Spirulina was cultured in Selenium solution and the total concentration was determined with isotope dilution technique. Low-molecular-weight-Selenium species for the water extract of Spirulina were separated and quantified with HPLC ICP/MS. Water extraction was used first and then protein enzyme (protease XIV) was used to digest and extract for the Se species in both water extract and residue. The total Se was $414.9{\pm}4.0{\mu}g\;g^{-1}$ and 77% existed in water extract while 22% remained in residue. Se species in supernatant was mostly inorganic selenate ($222.7{\mu}g\;g^{-1}$). After hydrolysis of protein, SeCys ($15.20{\mu}g\;g^{-1}$) and SeMet ($12.13{\mu}g\;g^{-1}$) were found. In residue, SeCys and SeMet were found with little inorganic Se. After protein hydrolysis of residue, more of Selenoamino acids SeCys ($9.35{\mu}g\;g^{-1}$) and SeMet ($18.23{\mu}g\;g^{-1}$) in addition to MeSeCys ($1.5{\mu}g\;g^{-1}$) were found. It is thought that inorganic selenium is mostly adsorbed on the surface of spirulina and can be easily removed by a simple distilled water extraction while most of organo-seleniums are remained in residue.

• Analytical Science and Technology
• /
• v.35 no.6
• /
• pp.256-266
• /
• 2022

It is important to determine the concentration of long-lived radionuclides (e.g., ¹²⁹I) in nuclear waste to ensure safety when handling it. To analyze nuclides in a solid sample (e.g., concrete and soil), it is essential to effectively separate and purify the nuclides of interest in the sample. This study reports the comprehensive efforts made to validate the analytical procedure for ¹²⁹I detection in solid samples, using a high-temperature combustion furnace. ¹²⁹I volatilized from the sample collected in 0.01 M HNO₃ solution with a reducing agent (e.g., NaHSO₃) and was rapidly measured by ICP-MS. Analytical conditions, such as pyrolysis temperature and types of mobile phase gas, catalyst, and trapping solution, were optimized to obtain a high recovery rate of spiked ¹²⁹I. Finally, the optimized method was applied for the simultaneous analysis of other volatile radionuclides, such as ³H and ¹⁴C. The performance test results for the optimized method confirmed that the LSC (for ³H and ¹⁴C) and ICP-MS (for ¹²⁹I) measurements, with the separation of volatile nuclides using a high-temperature combustion furnace, were reliable.