• Journal of Surface Science and Engineering
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• v.55 no.6
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• pp.441-447
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• 2022

Silicon-based materials are one of the most promising anode active materials in lithium-ion battery. A carbon layer decorated on the surface of silicon particles efficiently suppresses the large volume expansion of silicon and improves electrical conductivity. Carbon coating through chemical vapor deposition (CVD) is one of the most effective strategies to synthesize carbon- coated silicon materials suitable for mass production. Herein, we synthesized carbon coated SiOx via pilot scale CVD reactor (P-SiO_x@C) and carbon coated SiO_x via industrial scale CVD reactor (I-SiO_x@C) to identify physical characteristic changes according to the CVD capacity. Reduced size silicon domains and local non-uniform carbon coating layer were detected in I-SiO_x@C due to non-uniform temperature distribution in the industrial scale CVD reactor with large capacity, resulting in increased surface area due to severe electrolyte consumption.

• Applied Biological Chemistry
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• v.2
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• pp.45-52
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• 1961

The decomposition of malathion in dust for mulations prepared from four Korean tales as carriers during storage period has been studied. Amberlite CG-120, a cation exchange resin . which has higher cation exchange capacity than tales, was also used as a carrier in hope of finding out the effect of nagative charge upon the decomposition of malathion. Besides the original talc powders obtained directly from the mines, the hydrogen ion saturated forms were also used as carriers for comparisonal study. The saturated ions for the resin were hydrogen, sodium and magnesium. As the physical properties of the tales, colloid content, water adsorption capacity, PH, specific surface, phosphate fixing capacity and exchangeable canons were determined, and these properties were correlated with the amount of the decomposition. Following results were obtained from the experiment. 1. The malathion in the talc in dust was found to decompose around 10-15% ofthe total withina month. About 50% of the decom position that took place after a month was found to occur within a week. 2. The resin which has higher cation exchange capacity than the tales was highly effective in the decomposition of malathion compared with the tales. 3. In every case the saturation of the exchange complexes with hydrogen ion greatly accelerated the decomposition of malathion. 4. The most highly correlated physical properties with the decomposition were colloid content and specific surface of the tales. 5. The water adsorption and phosphate fixing capacities of the tales were found not to correlate with the amount of malathion decomposed. From the experimental results it was concluded that the active negative spots on the colloidal tales or the resin attract the electropositive phosphorus atom in a malathion molecule thereby inducing the decomposition easier. The presence of hydrogen ion nearby might cause a catalytic effect in the decomposition of malathion.

• Applied Chemistry for Engineering
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• v.31 no.3
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• pp.237-257
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• 2020

The role of nano bio-composites precursor to chitosan are innumerable and are known for having different applications in various branches of physical sciences. The application to the sensor development is relatively new, where only few literature works are available to address the specific and critical analysis of nanocomposites in the subject area. The bio-composites are potential and having greater affinity towards the heavy metals and several micro-pollutants hence, perhaps are having wider implications in the low or even trace level detection of the pollutants. The nano-composites could show good selectivity and suitability for the detection of the pollutants as they are found in the complex matrix. However, the greater challenges are associated using the bio-composites, since the biomaterials are prone to be oxidized or reduced at an applied potential and found to be a hinderance for the detection of target pollutants. In addition, the materials could proceed with a series of electrochemical reactions, which could produce different by-products in analytical applications, resulting in several complex phenomena in electrochemical processes. Therefore, this review addresses critically various aspects of an evaluation of nano bio-composite materials in the electrochemical detection of heavy metals and micro-pollutants from aqueous solutions.

• Applied Chemistry for Engineering
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• v.19 no.5
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• pp.547-553
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• 2008

To achieve the ideal performances of paint film, resins and hardeners have to be chosen and designed in a proper way depending on the exposure circumstance of substrate and the requested physical properties. Six different kinds of clear paints were made in this experiment using alkyd polyol, polyester polyol, polyester modified acrylic polyol and another 3 acrylic polyol resins whose $T_g$ and OH value were partially modified. Then the tests for chemical, physical, and mechanical properties were measured after forming the paint films using aliphatic and aromatic polyisocyanate. The viscosity and elasticity of paint film were then measured in terms of gel point and $tan{\delta}$ using Rheometer and DMA. Through this viscoelastic characteristic test of polyurethane resin, we were able to choose the adequate resins and hardeners which are the most important in the top and primer painting system of urethane paint and, as a result of observing the physical, mechanical, and chemical properties of paint film by urethane, we have finally reached the conclusion that we could apply the proper polyol to top and primer paint for developing the polyurethane paint system.

• Nuclear Engineering and Technology
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• v.54 no.1
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• pp.234-243
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• 2022

This study aims to characterize the irradiated RBMK-1500 nuclear graphite in terms of both structural and radiological properties. The experimental results of morphological and structural analysis of the irradiated graphite samples by using SEM, Raman spectroscopy as well as the theoretical evaluation of primary displacement damage are presented. Moreover, the experimental and theoretical evaluation of the neutron flux is provided and the presence of several γ emitters in the analyzed graphite samples is assessed. Furthermore, the improved version of rapid analysis method for ¹⁴C activity determination is applied and the experimentally obtained results are compared with calculated ones. Results indicate that structural changes are uniform enough in all the analyzed samples. However, the distribution of radionuclides is non-homogeneous in the irradiated RBMK-1500 reactor graphite matrix. The comprehensive understanding of both structural and radiological characteristics of nuclear graphite is very important when dealing with decision about irradiated graphite waste management strategy or treatment options prior to its final disposal.

• Bulletin of the Korean Chemical Society
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• v.34 no.4
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• pp.1039-1042
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• 2013

Polyynes were prepared by liquid laser ablation of a graphite target in deionized water at various physical conditions such as laser power (20 and 40 mJ/pulse) and ablation wavelengths (355, 532, and 1064 nm). The effects of physical parameters on the linear carbon chain length were examined by analyzing the densities of polyynes with different carbon numbers ($C_6H_2$, $C_8H_2$, and $C_{10}H_2$) as well as their branching ratios. We concluded the photophysical processes turned out to play a more significant role than thermal ones in the formation of polyynes.

• Elastomers and Composites
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• v.27 no.4
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• pp.247-254
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• 1992

The purpose of this dissertation is to study the vulcanization characteristics, compression set and other physical properties of NBR vulcanizates according to the various plasticizer and its content. Vulcanization characteristics were investigated by using cure that has obtained by means of rheometer and Mooney viscometer. The result of physical properties, vulcanization characteristics are as fellows. 1. The results of test for optimum cure time in vulcanization characteristics of NBR compounds indicated the rapidity of scorch time according to the increase of amounts of plasticizer. 2. In the test of compression set property, LCR was the best effect. 3. In the test of oil resistance, LCR was the best effect.

• The Korean Journal of Ceramics
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• v.2 no.2
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• pp.76-82
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• 1996

PLZT ceramics having two nominal compositions, $Pb_{1-3x/2}La_xV_{x/2}(Zr_{03}Ti_{03})O_3$ and $Pb_{1-x}La_x(Zr_{0.2}Ti_{0.5})_{1-x/4}V_{x/4}O_3$ (V: vacancy) with x=0.00~0.30, were prepared. The physical, structural, and dielectric properties were investigated by X-ray diffraction, scanning electron microscopy, Raman spectroscopy, and measurements of bulk density and dielectric constant. The two series with A-stie and B-site vacancies showed different physical, structural, dielectric properties, and, specially, Curie temperature. In comparison to PLZT with B-site vacancies, PLZT with A-site vacancies showed high Curie temperatures and low maxima of dielectric constant. Consequently, it is evident that the properties of PLZT ceramics depend on the vacancy formula adopted as a batch composition in preparation.

• Applied Chemistry for Engineering
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• v.9 no.5
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• pp.763-767
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• 1998

Cholesterol-containing surfactant was synthesized, and it was sonicated with monomer [tetradeca(ethylene glycol) diacrylate] in water to from a vesicle solution. This vesicle solution was dried to construct a membrane which had a molecular multilayer structure. The monomer which stay in this membrane was polymerized with photoinitiation, and then surfactant was extracted by organic solvent. The physical properties of the two dimensional polymer network were measured, and these physical properties are tensile strength, elongation, and swelling.

• Carbon letters
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• v.10 no.4
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• pp.293-299
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• 2009

Potassium hydroxide activated carbons were prepared from Egyptian petroleum cokes with different KOH/coke ratios and at different activation temperatures and times. The textural properties were determined by adsorption of nitrogen at $-196^{\circ}C$. The adsorption of iodine and methylene blue was also investigated at $30^{\circ}C$. The surface area and the non-micropore volume increased whereas the micropore volume decreased with the increase of the ratio KOH/coke. Also the surface area and porosity increased with the rise of activation temperature from 500 to $800^{\circ}C$. Textural parameter considerably increased with the increase of activation time from 1 to 3 h. Further increasing of activation time from 3 to 4 h was associated with a less pronounced increase in textural parameters. The adsorption of iodine shows the same trend of surface area and porosity change exhibited by nitrogen adsorption, with KOH/coke ratio and temperature of activation. Adsorption of methylene blue follows pseudo-first-order kinetics and its equilibrium adsorption follows Langmuir and D-R models.