• Environmental Analysis Health and Toxicology
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• 제28권
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• pp.14.1-14.9
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• 2013

Objectives This study was conducted to determine whether nano-sized carbon black exposure results in greater damage in high fat diet-induced overweight rats than normal weight ones and to identify the possible causes of any differences. Methods Two groups of Sprague-Dawley rats allocated by body weight (normal and overweight) were exposed to aerosolized nano-sized carbon black for 6 hours a day, 5 days per week over a 4-week period. Differential cell counts, lactate dehydrogenase (LDH) activities and albumin concentrations were measured in bronchoalveolar lavage (BAL) fluid, and histopathological findings in the lungs were evaluated. Tumor necrosis factor-alpha (TNF-${\alpha}$) and interleukin (IL)-6 were measured in BAL fluid and supernatants of lipopolysaccharide(LPS)-stimulated lymphocyte culture. Results Rats exposed to high concentrations of nano-sized carbon black showed significantly increased (p <0.05) polymorphonuclear leukocyte number and LDH activity in the BAL fluid from both overweight and normal rats. Mild histopathological changes were observed in normal rats irrespective of carbon black concentrations. However, severe histological scores were found in overweight rats ($1.75{\pm}0.46$, $2.25{\pm}0.46$, and $2.88{\pm}0.35$ after low, medium, and high concentration exposures). Proinflammatory cytokine levels of TNF-${\alpha}$ and IL-6 were significantly higher in the supernatant of LPS-stimulated lymphocytes of overweight rats, whereas there was no significant difference in the BAL fluid between normal and overweight rats. Conclusions Inflammation and damage to lungs exposed to nano-sized carbon black was more severe in high fat diet-induced overweight rats compared to normal rats.

• 폴리머
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• 제26권3호
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• pp.367-374
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• 2002

본 연구에서는 나노 입자의 카본블랙을 결정성 고분자에 분산시켜 특정한 온도에서 저항이 급격하게 증가하는 positive temperature coefficient resistance (PTCR) 특성을 연구하였다. 열가소성 수지를 이용한 PTCR 소재를 열처리에 의하여 고분자의 큐리온도를 조절할 수 있었다. 나노입자 카본블랙이 고분자 구조내에 고르게 분산이 되지 않고, 카본블랙의 함량이 과다하면 negative temperature coefficient resistance (NTCR) 현상이 발생하였다. 카본블랙의 함량과 내부전압을 조절함에 따라 발열 온도를 선정할 수 있었다. 카본블랙의 함량에 따라 전기 전도성이 다르게 나타났으며, 20 wt% 이상에서는 저항이 거의 일정하게 나타난다는 것을 확인하였다. 본 연구에서 제조된 PTCR 소재는 반복적인 가열 냉각에 따른 상온에서의 초기 저항의 변화가 거의 없어 재현성을 확인하였으며, 초기의 낮은 저항에 의한 순간적인 발열에 의하여 저온에서의 PTCR 성능이 향상되었다.

• Toxicological Research
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• 제29권2호
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• pp.121-127
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• 2013

Nanotoxicological research has shown toxicity of nanomaterials to be inversely related to particle size. However, the contribution of agglomeration to the toxicity of nanomaterials has not been sufficiently studied, although it is known that agglomeration is associated with increased nanomaterial size. In this study, we prepared aerosols of nano-sized carbon black by 2 different ways to verify the effects of agglomeration on the toxicity and deposition of nano-sized carbon black. The 2 methods of preparation included the carbon black dispersion method that facilitated clustering without sonication and the carbon black dispersion method involving sonication to achieve scattering and deagglomeration. Male Sprague-Dawley rats were exposed to carbon black aerosols 6 hr a day for 3 days or for 2 weeks. The median mass aerodynamic diameter of carbon black aerosols averaged $2.08{\mu}m$ (for aerosol prepared without sonication; group N) and $1.79{\mu}m$ (for aerosol prepared without sonication; group S). The average concentration of carbon black during the exposure period for group N and group S was $13.08{\pm}3.18mg/m^3$ and $13.67{\pm}3.54mg/m^3$, respectively, in the 3-day experiment. The average concentration during the 2-week experiment was $9.83{\pm}3.42mg/m^3$ and $9.08{\pm}4.49mg/m^3$ for group N and group S, respectively. The amount of carbon black deposition in the lungs was significantly higher in group S than in group N in both 3-day and 2-week experiments. The number of total cells, macrophages and polymorphonuclear leukocytes in the bronchoalveolar lavage (BAL) fluid, and the number of total white blood cells and neutrophils in the blood in the 2-week experiment were significantly higher in group S than in normal control. However, differences were not found in the inflammatory cytokine levels (IL-$1{\beta}$, TNF-${\alpha}$, IL-6, etc.) and protein indicators of cell damage (albumin and lactate dehydrogenase) in the BAL fluid of both group N and group S as compared to the normal control. In conclusion, carbon black aerosol generated by sonication possesses smaller nanoparticles that are deposited to a greater extent in the lungs than is aerosol formulated without sonication. Additionally, rats were narrowly more affected when exposed to carbon black aerosol generated by sonication as compared to that produced without sonication.

• 폴리머
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• 제26권6호
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• pp.812-820
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• 2002

본 연구에서는 나노입자인 카본블랙을 고분자에 분산시킨 복합체를 각각 용액혼합과 용융혼합을 이용하여 positive temperature coefficient (PTC) 특성을 연구하였다. 전도성 나노입자인 카본블랙과 고분자 복합체의 저항 통전 (threshold)은 용융혼합하였을 때 카본블랙의 함량이 35wt% 이상에서 나타났으며. 용액혼합에서는 카본블랙 함량이 40 wt% 이상에서 나타났다. Ethyl-one vinylacetate copolymer (EVA)의 경우, 온도의 변화에 따라서 저항이 서서히 증가하다가 용융점 근처에서 극대값을 나타내었지만, high density polyethylene (HDPE)의 경우는 저항이 온도의 변화에 따라 일정하다가 용융점 근처에서 증가하기 시작하여 용융점에서 극대값을 나타내었다. 통전 후의 낮은 저항과, scanning electron microscopy (SEM)으로 관찰한 결과로부터 전도성 나노입자의 카본블랙 분산방법에서 용액혼합의 분산 정도가 용융혼합 못지않게 나타났다. PTC 소재에 전류인가시 큐리온도에서 1차적으로 저항이 증가하였으며, 고분자의 용융점에서 2차적으로 트립온도가 될 때까지 저항이 증가하다가 트립온도 이후에는 저항이 일정하게 유지됨을 알 수 있었다.

• Safety and Health at Work
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• 제2권3호
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• pp.282-289
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• 2011

Objectives: We sought to establish a novel method to generate nano-sized carbon black particles (nano-CBPs) with an average size smaller than 100 nm for examining the inhalation exposure risks of experimental rats. We also tested the effect of nano-CBPs on the pulmonary and circulatory systems. Methods: We used chemical vapor deposition (CVD) without the addition of any additives to generate nano-CBPs with a particle size (electrical mobility diameter) of less than 100nm to examine the effects of inhalation exposure. Nano-CBPs were applied to a nose-only inhalation chamber system for studying the inhalation toxicity in rats. The effect on the lungs and circulatory system was determined according to the degree of inflammation as quantified by bronchoalveolar lavage fluid (BALF). The functional alteration of the hemostatic and vasomotor activities was measured by plasma coagulation, platelet activity, contraction and relaxation of blood vessels. Results: Nano-CBPs were generated in the range of 83.3-87.9 nm. Rats were exposed for 4 hour/day, 5 days/week for 4 weeks to $4.2{\times}10^6$, $6.2{\times}10^5$, and $1.3{\times}10^5$ particles/$cm^3$. Exposure of nano-CBPs by inhalation resulted in minimal pulmonary inflammation and did not appear to damage the lung tissue. In addition, there was no significant effect on blood functions, such as plasma coagulation and platelet aggregation, or on vasomotor function. Conclusion: We successfully generated nano-CBPs in the range of 83.3-87.9 nm at a maximum concentration of $4.2{\times}10^6$ particles/$cm^3$ in a nose-only inhalation chamber system. This reliable method can be useful to investigate the biological and toxicological effects of inhalation exposure to nano-CBPs on experimental rats.

• 한국수소및신에너지학회논문집
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• 제22권4호
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• pp.504-511
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• 2011

Nano-sized Sn powder was prepared by pulsed wire evaporation method. The Sn powder and carbon black were charged in jar and ball milled. The milling time was varied with 10 min., 1h, 2h, and 4h, respectively. The milled powders were dried and the shape and size were observed by FE-SEM. Nano-sized Sn powders were plastic-deformed and agglomerated by impact force of balls and heat generated during the SPEX milling. The agglomerated Sn powder also consisted of many nano-sized particles. Initial discharge capacities of milled Sn electrode powders with carbon powder were milled for 10 min., 1h, 2h, and 4h were 787, 829, 827, and 816 mAh/g, respectively. After 5 cycle, discharge capacities of Sn electrode powders with carbon powder milled for 10 min., 1h, 2h, and 4h decreased as 271, 331, 351, and 287 mAh/g, respectively. Because Sn electrode powders milled for 2h constist of uniform and fine size, the cyclability of coin cell made of this powders is better than others.

• Carbon letters
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• 제7권2호
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• pp.87-96
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• 2006

This paper describes the physical properties of filled Nylon6 composites resin with nano-sized carbon black particle and graphite nanofibers prepared by melt extrusion method. In improving adhesions between resin and fillers, the surface of the carbon filler materials were chemically modified by thermo-oxidative treatments and followed by treatments of silane coupling agent. Crystallization temperature and rate of crystallization increased with increases in filler concentration which would act as nuclei for crystallization. The silane treatments on the filler materials showed effect of reduction in crystallization temperature, possibly from enhancement in wetting property of the surface of the filler materials. Percolation transition phenomenon at which the volume resistivity was sharply decreased was observed above 9 wt% of carbon black and above 6 wt% of graphite nanofiber. The graphite nanofibers contributed to more effectively in an increase in electrical conductivity than carbon black did, on the other hand, the silane coupling agent negatively affected to the electrical conductivity due to the insulating property of the silane. Positive temperature coefficient (PTC) phenomenon, was observed as usual in other composites, that is, temperature increase results conductivity increase. The dispersity of the fillers were excellently approached by melt extrusion of co-rotational twin screw type and it could be illustrated by X-ray diffraction and SEM.

• 한국수소및신에너지학회논문집
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• 제19권2호
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• pp.163-170
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• 2008

Carbon nanofibers with nano-sized structures were evaluated as a active material using supercacitor electrode which could store electrochemical energy reversibly. A feasibility of EDLC electrode was estimated with specific surface area measurement by BET method and mesopore structure of carbon nanofiber surface could be explained electrochemical absorption-desorption in aqueous electrolyte. A capacitance of carbon nanofiber electrode was increased gradually, depending on the ratio of Ketjenblack as a conducting material. Ketjen Black $20{\sim}25\;wt.%$ ratio in electrode was observed a suitable amount of conducting material by cyclic voltametry results.

• 한국재료학회지
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• 제23권4호
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• pp.246-249
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• 2013

Nano-sized ${\beta}$-SiC nanoparticles were synthesized combined with a sol-gel process and a carbothermal process. TEOS and carbon black were used as starting materials for the silicon source and carbon source, respectively. $SiO_2$ nanoparticles were synthesized using a sol-gel technique (Stober process) combined with hydrolysis and condensation. The size of the particles could be controlled by manipulating the relative rates of the hydrolysis and condensation reactions of tetraethyl orthosilicate (TEOS) within the micro-emulsion. The average particle size and morphology of synthesized silicon dioxide was about 100nm and spherical, respectively. The average particles size and morphology of the used carbon black powders was about 20nm and spherical, respectively. The molar ratio of silicon dioxide and carbon black was fixed to 1:3 in the preparation of each combination. $SiO_2$ and carbon black powders were mixed in ethanol and ball-milled for 12 h. After mixing, the slurries were dried at $80^{\circ}C$ in an oven. The dried powder mixtures were placed in alumina crucibles and synthesized in a tube furnace at $1400{\sim}1500^{\circ}C$ for 4 h with a heating rate of $10^{\circ}C$/min under flowing Ar gas (160 cc/min) and furnace cooling down to room temperature. SiC nanoparticles were characterized by XRD, TEM, and SAED. The XRD results showed that high purity beta silicon carbide with excellent crystallinity was synthesized. TEM revealed that the powders are spherical shape nanoparticles with diameters ranging from 15 to 30 nm with a narrow distribution.

• 한국세라믹학회지
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• 제49권6호
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• pp.625-630
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• 2012

Highly porous silicon carbide (SiC) ceramics were fabricated from polysiloxane, SiC and carbon black fillers, AlN-$Y_2O_3$ additives, and poly (ether-co-octene) (PEOc) and expandable microsphere templates. Powder mixtures with a fixed PEOc content (30 wt%) and varying SiC filler contents from 0-21 wt% were compression-molded. During the pyrolysis process, the polysiloxane was converted to SiOC, the PEOc generated a considerable degree of interconnected porosity, and the expandable microspheres generated fine cells. The polysiloxane-derived SiOC and carbon black reacted and synthesized nano-sized SiC with a carbothermal reduction during a heat-treatment. Subsequent sintering of the compacts in a nitrogen atmosphere produced highly porous SiC ceramics with porosities ranging from 78 % to 82 % and a flexura lstrength of up to ~7 MPa.