• 한국환경농학회지
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• 제29권4호
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• pp.402-407
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• 2010

Zerovalent iron (ZVI) is one of the most commonly used metallic reducing agents for the treatment of toxic contaminants in wastewater. Traditional ZVIs are less effective than nanoscale ZVI (nZVI) due to prolonged reaction time. However, the reactivity can be significantly increased by reducing the size of ZVI particles to nanoscale. In this study, nZVI particles were synthesized under laboratory condition and their efficiency in removing hexavalent chromium (Cr(VI)) from aqueous solutions were compared with commercially available ZVI particles. The results showed that the synthesized nZVI particles (SnZVI) reduced >99% of Cr(VI) at the application rate of 0.2% (w/v), while commercial nZVI (CnZVI) particles resulted in 59.6% removal of Cr(VI) at the same application rate. Scanning electron micrographs (SEM) and energy dispersive spectra (EDS) of the nZVI particles revealed the formation of Fe-Cr hydroxide complex after reaction. Overall, the SnZVI particles can be used in treating chromium contaminated wastewater.

• Korea-Australia Rheology Journal
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• 제17권2호
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• pp.35-40
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• 2005

Nanofluid is a novel heat transfer fluid prepared by dispersing nanometer-sized solid particles in traditional heat transfer fluid to increase thermal conductivity and heat transfer performance. In this research we have considered the rheological properties of nanofluids made of CuO particles of 10-30nm in length and ethylene glycol in conjunction with the thermal conductivity enhancement. When examined using TEM, individual CuO particles have the shape of prolate spheroid of the aspect ratio of 3 and most of the particles are under aggregated states even after sonication for a prolonged period. From the rheological property it has been found that the volume fraction at the dilute limit is 0.002, which is much smaller than the value based on the shape and size of individual particles due to aggregation of particles. At the semi-dilute regime, the zero shear viscosity follows the Doi-Edwards theory on rodlike particles. The thermal conductivity measurement shows that substantial enhancement in thermal conductivity with respect to particle concentration is attainable only when particle concentration is below the dilute limit.

• Toxicological Research
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• 제33권4호
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• pp.305-313
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• 2017

Accumulating epidemiological evidence indicates that exposure to fine air pollution particles (APPs) is associated with a variety of adverse health effects. However, the exact physiochemical properties and biological toxicities of fine APPs are still not well characterized. We collected four types of fine particle (FP) (diesel exhaust particles [DEPs], natural organic combustion [NOC] ash, synthetic organic combustion [SOC] ash, and yellow sand dust [YSD]) and investigated their physicochemical properties and in vitro biological toxicity. DEPs were almost entirely composed of ultrafine particles (UFPs), while the NOC, SOC, and YSD particles were a mixture of UFPs and FPs. The main elements in the DEPs, NOC ash, SOC ash, and YSD were black carbon, silicon, black carbon, and silicon, respectively. DEPs exhibited dose-dependent mutagenicity even at a low dose in Salmonella typhimurium TA 98 and 100 strains in an Ames test for genotoxicity. However, NOC, SOC, and YSD particles did not show any mutagenicity at high doses. The neutral red uptake assay to test cell viability revealed that DEPs showed dose-dependent potent cytotoxicity even at a low concentration. The toxicity of DEPs was relatively higher than that of NOC, SOC, and YSD particles. Therefore, these results indicate that among the four FPs, DEPs showed the highest in vitro biological toxicity. Additional comprehensive research studies such as chemical analysis and in vivo acute and chronic inhalation toxicity tests are necessary to determine and clarify the effects of this air contaminant on human health.

• 상하수도학회지
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• 제18권5호
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• pp.649-655
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• 2004

The behavior of biological particles in DAF (dissolved air flotation) process was analyzed by employing PBT (Population balance theory). After decline growth phase of activated sludge, the value of the initial collision-attachment efficiency was increased over than 0.35 corresponding relatively high value in the whole life cycle of microorganism. For practical application of DAF as a solid separation process. It is desirable that microbial particles should be operated to perform high solid removal efficiency in biological wastewater treatment.

• Asian Journal of Atmospheric Environment
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• 제5권3호
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• pp.152-156
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• 2011

Viable bacteria on water-insoluble airborne particles were detected in the urban atmosphere of Kumamoto ($134^{\circ}45'E$, $32^{\circ}28'N$), Japan, in autumn 2008. Airborne particles were collected onto film-covered Cu meshes under clear weather conditions. The samples were stained by fluorescent stains, and then viewed and photographed with an epifluorescent microscope. Non-biological and bacterial parts in particles larger than 0.8 ${\mu}m$ were distinguished by their morphologies, fluorescent colors and fluorescent intensities. Bacterial viable statuses were discriminated according to cell membrane damage. In total, 2681 particles were investigated and it was found that 78 airborne particles were associated with bacteria. Viable bacteria were identified on 48 particles. A few particles carried multiple viable bacteria. These results provide the evidence that airborne particles act as carriers of viable bacteria in the atmosphere.

• 한국생물공학회:학술대회논문집
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• 한국생물공학회 2000년도 춘계학술발표대회
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• pp.442-445
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• 2000

Amphiphilic polyurethane(APU) particle is a polymeric surfactant, and could increase the solubility of 2-methylnaphthalene significantly. 2-Methylnaphthalene was recovered by the precipitation of APU particles and was degraded by Acinetobacter sp. K2-2. APU particle was recovered and reused after treatment of triethylamine.

• 대한환경공학회지
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• 제27권7호
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• pp.771-776
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• 2005

최근 항균 성능이 뛰어나면서도 인체에 유해하지 않은 나노 사이즈 은 입자를 이용한 항균 제품 개발 및 연구가 활발히 이루어지고 있음에 따라, 나노 사이즈의 은 입자를 보다 쉬운 방법으로 균일하게 제조하고, 그 특성을 평가하는데 많은 관심이 집중되고 있다. 본 연구에서는 은 이온의 광환원을 통해 나노 은 입자를 $15{\sim}20\;nm$ 크기로 균일하게 제조한 뒤, 나노 은 입자의 농도, pH, 온도가 변화함에 따른 항균 특성을 살펴보고 이를 정량적으로 평가, 은 이온의 항균 특성과 비교하였다. 또한 주사 전자 현미경과 투과 전자 현미경을 통하여 나노 은 입자의 미생물 불활성화 특성을 은 이온의 미생물 불활성화 특성과 비교하였다. 주요 결과로는 나노 은 입자의 항균 효과는 동일한 은 농도를 기준으로 하였을 때 은 이온의 항균 효과에 비하여 약 20배 정도 적은 것을 알 수 있었다. 또한 나노 은 입자의 농도, 온도가 높을수록 항균 성능은 향상됨을 알 수 있었으며 이는 은 이온의 실험 결과와 일치한다. 그러나 나노 은 입자의 항균 성능은 높은 pH에서 향상된 반면, 은 이온의 경우 pH 변화에 따른 항균 성능 변화가 관찰되지 않았다. 나노 은 입자와 은 이온에 의해 불활성화된 미생물을 주사 전자 현미경과 투과 전자 현미경으로 관찰한 결과, 나노 은 입자는 미생물 세포막을 크게 손상시키는 반면, 은 이온은 그렇지 않았다. 은 이온의 경우 은 이온이 미생물 안으로 흡수되어 세포질막을 손상시켜 미생물을 불활성화 시키는 것으로 알 수 있었다.

• Molecules and Cells
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• 제40권5호
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• pp.339-345
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• 2017

Retroviral and lentiviral vectors are mostly pseudotyped and often purified and concentrated via ultracentrifugation. In this study, we quantified and compared the stabilities of retroviral [murine leukemia virus (MLV)-based] and lentiviral [human immunodeficiency virus (HIV)-1-based] vectors pseudotyped with relatively mechanically stable envelope proteins, vesicular stomatitis virus glycoproteins (VSVGs), and the influenza virus WSN strain envelope proteins against ultracentrifugation. Lentiviral genomic and functional particles were more stable than the corresponding retroviral particles against ultracentrifugation when pseudotyped with VSVGs. However, both retroviral and lentiviral particles were unstable when pseudotyped with the influenza virus WSN strain envelope proteins. Therefore, the stabilities of pseudotyped retroviral and lentiviral vectors against ultracentrifugation process are a function of not only the type of envelope proteins, but also the type of viral internal core (MLV or HIV-1 core). In addition, the fraction of functional viral particles among genomic viral particles greatly varied at times during packaging, depending on the type of envelope proteins used for pseudotyping and the viral internal core.

• Journal of Pharmaceutical Investigation
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• 제35권2호
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• pp.89-94
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• 2005

The micron or nano-sized lysozyme as a model protein drug was prepared using solution enhanced dispersion by supercritical fluid (SEDS) process at various conditions (e.g., solvent, temperature and pressure) to investigate the feasibility of pulmonary protein drug delivery. The lysozyme particles prepared were characterized by laser diffraction particle size analyzer, scanning electron microscopy (SEM) and powder X-ray diffractometry (PXRD). The biological activity of lysozyme particles after/before SEDS process was also examined. Lysozyme was precipitated as spherical particles. The precipitated particles consisted of 100 - 200 nm particles. Particle size showed the precipitates to be agglomerates with primary particles of size $1\;-\;5 \;{\mu}m$. The biological activity varied between 38 and 98% depending on the experimental conditions. There was no significant difference between untreated lysozyme and lysozyme after SEDS process in PXRD analysis. Therefore, the SEDS process could be a novel method to prepare micron or nano-sized lysozyme particles, with minimal loss of biological activity, for the pulmonary delivery of protein drug.

• Toxicological Research
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• 제28권4호
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• pp.209-216
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• 2012

The biological activity of particles is largely dependent on their size in biological systems. Dispersion in the aqueous phase has been both a critical impediment to and a prerequisite for particle studies. Carbon black has been used as a surrogate to investigate the biological effects of carbonaceous particles. Here, biocompatible methods were established to disperse carbon black into ultrafine and fine particles which are generally distinguished by the small size of 100 nm. Carbon black with a distinct particle size, N330 and N990 were suspended in blood plasma, cell culture media, Krebs-Ringer's solution (KR), or physiological salt solution (PSS). Large clumps were observed in all dispersion preparations; however, sonication improved dispersion - averaged particle sizes for N330 and N990 were $85.0{\pm}42.9$ and $112.4{\pm}67.9$ nm, respectively, in plasma; the corresponding sizes in culture media were $84.8{\pm}38.4$ and $164.1{\pm}77.8$ nm. However, sonication was not enough to disperse N330 less than 100 nm in either KR or PSS. Application of Tween 80 along with sonication reduced the size of N330 to less than 100 nm, and dispersed N990 larger than 100 nm ($73.6{\pm}28.8$ and $80.1{\pm}30.0$ nm for N330 and $349.5{\pm}161.8$ and $399.8{\pm}181.1$ nm for N990 in KR and PSS, respectively). In contrast, 1,2-dipalmitoyl-sn-glycero-3-phosphocholine (DPPC) exhibited little effect. Electron microscopy confirmed the typical aciniform structure of the carbon arrays; however, zeta potential measurement failed to explain the dispersibility of carbon black. The methods established in this study could disperse carbon black into ultrafine and fine particles, and may serve as a useful model for the study of particle toxicity, particularly size-related effects.