• Clean Technology
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• v.30 no.1
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• pp.62-67
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• 2024

In this study, an alkali metal Na was introduced into iron-based catalysts used in the carbon dioxide-based Fischer-Tropsch process by wet impregnation and physical mixing methods to compare their performance. The as-prepared catalysts were evaluated for reactivity at 3.5 MPa, 330 ℃, feed ratio of H₂/CO₂ = 3 with a space velocity of 4,000 mL h^-1 g_cat^-1. Comparing the two catalysts, it was found that Na was uniformly distributed throughout the catalyst when wet-impregnated, but Na for physically mixed catalyst was relatively located on the surface of the catalyst. In addition, the wet-impregnated catalyst showed higher liquid hydrocarbon (C₅₊) yield and lower CO selectivity. In conclusion, the effect of Na distribution in the catalyst on the reaction was identified and can be controlled by the introduction method.

• Journal of Microbiology and Biotechnology
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• v.34 no.7
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• pp.1419-1424
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• 2024

Secretin PilQ is an antigenically conserved outer membrane protein that is present in most meningococci and PorA is a major protein that elicits bactericidal immune response in humans following natural disease and immunization. In the present study, BALB/c mice were immunized subcutaneously with rPilQ406-770 or rPorA together with Freund's adjuvant (FA). Serum antibody responses to serogroup A and B Neisseria meningitides whole cells or purified proteins and functional activity of antibodies were determined by ELISA and serum bactericidal assay (SBA), respectively. Serum IgG responses were significantly increased in the immunized group with rPilQ406-770 or rPorA together with FA compared to control groups. IgG antibody response of mice immunized with rPilQ406-770 was significantly more than mice immunized with rPorA (OD at 450 nm was 1.6 versus 0.83). The booster injections were effective in increasing the responses of antirPilQ406-770 or anti-rPorA IgG significantly. Antisera produced against rPilQ406-770 or rPorA demonstrated strong surface reactivity to serogroup B N. meningitides in comparison with control groups. Antisera raised against rPorA or rPilQ406-770 and FA demonstrated SBA titers from 1/1024 to 1/2048 against serogroup B. The strongest bactericidal activity was detected in sera from mice immunized with rPilQ406-770 mixed with FA. These results suggest that rPilQ406-770 is a potential vaccine candidate for serogroup B N. meningitidis.

• Membrane Journal
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• v.21 no.1
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• pp.46-54
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• 2011

In this study, combined effect of airflow rate, $TiO_2$ concentration, solution pH and $Ca^{+2}$ addition on HA (humic acid) fouling in submerged, photocatalytic hollow-fiber microfiltraiton was investigated systematically. Results showed that UV irradiation alone without $TiO_2$ nanoparticles could reduce HA fouling by 40% higher than the fouling obtained without UV irradiation. Compared to the HA fouling without UV irradiation and $TiO_2$ nanoparticles, the HA fouling reduction was about 25% higher only after the addition of $TiO_2$ nanoparticles. Both adsorptive and hydrophilic properties of $TiO_2$ nanoparticles for the HA can be involved in mitigating membrane fouling. It was also found that the aeration itself had lowest effect on fouling mitigation while the HA fouling was affected significantly by solution pH. Transient behavior of zeta potential at different solution pHs suggested that electrostatic interactions between HA and $TiO_2$ nanoparticles should improve photocatalytic efficiency on HA fouling. $TiO_2$ concentration was observed to be more important factor than airflow rate to reduce HA fouling, implying that surface reactivity on $TiO_2$ naoparticles should be important fouling mitigation mechanisms in submerged, photocatalyic microfiltraiton. This was further supported by investigating the effect of $Ca^{+2}$ addition on fouling mitigation. At higher pH (= 10), addition of $Ca^{+2}$ can play an important role in bridging between HA and $TiO_2$ nanoparticles and increasing surface reactivity on nanoparticles, thereby reducing membrane fouling.

• The Korean Journal of Blood Transfusion
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• v.29 no.3
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• pp.301-309
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• 2018

Background: If donors who were deferred due to the reactivity or grey zone in HBV surface antigen (HBsAg) assay want to donate blood again, they need to pass reentry tests. On the other hand, approximately half of the donors who are subject to the reentry tests cannot be reentered. This study examined the association between the sample to cutoff (S/Co) value of the HBsAg assay and the final results of the reentry test. Methods: This study analyzed the S/Co values of the HBsAg assay and the final results of the reentry tests for the 3,947 donors from January 2008 to December 2017 using the database of Blood Information Management System of the Korean Red Cross. Results: 1,767 donors (44.8%) were not reentered among 3,947 deferred donors. Among 1,585 donors showing ${\geq}10$ of the S/Co value in the HBsAg screening test, 1,542 donors (97.3%) were not reentered. The additional reentry tests were performed on 120 donors who were not reentered in the first reentry test; 98 donors (81.7%) were still not reentered. Overall, 4.6% of the donors showing a grey zone in the HBsAg assay were not reentered. Conclusion: The reentry test needs to be restricted for the deferred donors showing a more than 10 S/Co value. The application of the grey zone of current HBsAg assay will need to be continued to enhance the HBV-related blood safety.

• Journal of the Mineralogical Society of Korea
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• v.25 no.4
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• pp.185-195
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• 2012

Due to the high reduction and sorption capacity as well as the large specific surface area, nanosized mackinawite (FeS) is useful in reductively transforming chlorinated organic pollutants and sequestering toxic metals and metalloids. Due to the dynamic nature in its colloid stability, however, nanosized FeS may be washed out with the groundwater flow or result in aquifer clogging via particle aggregation. Thus, these nanoparticles should be modified such as to be built into permeable reactive barriers. This study employed coating methods in efforts to facilitate the installation of permeable reactive barriers of nanosized mackinawite. In applying the methods, nanosized mackinawite was coated on non-treated silica sand (NTS) and chemically treated silica sand (CTS). For both silica sands, the maximum coating of mackinawite occurred around pH 5.4, the condition of which was governed by (1) the solubility of mackinawite and (2) the surface charge of both silica and mackinawite. Under this pH condition, the maximum coating by NTS and CTS were found to be 0.101 mmol FeS/g and 0.043 mmol FeS/g respectively, with such elevated coatings by NTS likely linked with impurities (e.g., iron oxides) on its surface. Arsenite sorption experiments were performed under anoxic conditions using uncoated silica sands and those coated with mackinawite at the optimal pH to compare their reactivity. At pH 7, the relative sorption efficiency between uncoated NTS and coated NTS changed with the initial concentration of arsenite. At the lower initial concentration, uncoated NTS showed the higher sorption efficiency, whereas at the higher concentration, coated NTS exhibited the higher sorption efficiency. This could be attributed to different sorption mechanisms as a function of arsenite concentration: the surface complexation of arsenite with the iron oxide impurity on silica sand at the low concentration and the precipitation as arsenic sulfides by reaction with mackinawite coating at the high concentration. Compared to coated NTS, coated CTS showed the lower arsenite removal at pH 7 due to its relatively lower mackinawite coating. Taken together, our results indicate that NTS is a more effective material than CTS for the coating of nanosized mackinawite.

• Korean Chemical Engineering Research
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• v.52 no.6
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• pp.807-813
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• 2014

The Ag-impregnated activated carbon was produced from bamboo activated carbon by soaking method of silver nitrate solution. The carbonization and activation of raw material was conducted at $900^{\circ}C$. Soaking conditions are the variation of silver nitrate solution concentration (0.002~0.1 mol/L) and soaking time (maximum 24 h). The specific surface area and pore size distribution of the prepared activated carbons were measured. Also, NO and activated carbon reaction were conducted in a thermogravimetric analyzer in order to use for de-NOx agents of used activated carbon. Carbon-NO reactions were carried out with respect to reaction temperature ($20{\sim}850^{\circ}C$) and NO gas partial pressure (0.1~1.8 kPa). As results, Ag amounts are saturated within 2h, Ag amounts increased 1.95 mg Ag/g (0.2%)~ 88.70 mg Ag/g (8.87%) with the concentration of silver nitrate solution in the range of 0.002~0.1 mol/L. The specific volume and surface area of bamboo activated carbon of impregnated with 0.2% silver were maximum, but decreased with increasing Ag amounts of activated carbon due to pore blocking. In NO reaction, the reaction rate of impregnated bamboo activated carbon was retarded as compare with that of bamboo activated carbon. Measured reaction orders of NO concentration and activation energy were 0.63[BA], 0.69l[BA(Ag)] and 80.5 kJ/mol[BA], 66.4 kJ/mol[BA(Ag)], respectively.

• KSBB Journal
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• v.22 no.6
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• pp.414-420
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• 2007

Nanomaterials have been applied to various fields due to their advantageous characteristics such as high surface area, rapid diffusion, high specific surface areas, reactivity in liquid or gas phase, and a size close to biomacromolecules. Up to date, increased manufacturing and frequently use of the materials, however, revoke people's concerns on their hazard impact including toxicity the materials. Many research groups have carried out different protocols to evaluate toxic effects of nanomaterilas on different organisms, and consequently, nanomaterials are known to cytotoxicity. In this paper, we reviewed some of the most reports on toxic effects of several nanoparticles specifically on bacteria. There are numbers of reports focused on antibacterial effect of nanoparticles based on bacterial cell viability. Therefore, the application of each nanomaterial should be concerned with its toxicity and its toxic effect should be evaluated in terms of concentrations and sizes of the nanomaterials used, prior to use of a nanomaterial.

• Annals of Laboratory Medicine
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• v.38 no.6
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• pp.578-584
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• 2018

Background: Accurate, rapid, and cost-effective screening tests for hepatitis B virus (HBV) and hepatitis C virus (HCV) infection may be useful in laboratories that cannot afford automated chemiluminescent immunoassays (CLIAs). We evaluated the diagnostic performance of a novel rapid automated fluorescent lateral flow immunoassay (LFIA). Methods: A fluorescent LFIA using a small bench-top fluorescence reader, Automated Fluorescent Immunoassay System (AFIAS; Boditech Med Inc., Chuncheon, Korea), was developed for qualitative detection of hepatitis B surface antigen (HBsAg), antibody to HBsAg (anti-HBs), and antibody to HCV (anti-HCV) within 20 minutes. We compared the diagnostic performance of AFIAS with that of automated CLIAs-Elecsys (Roche Diagnostics GmbH, Penzberg, Germany) and ARCHITECT (Abbott Laboratories, Abbott Park, IL, USA)-using 20 seroconversion panels and 3,500 clinical serum samples. Results: Evaluation with the seroconversion panels demonstrated that AFIAS had adequate sensitivity for HBsAg and anti-HCV detection. From the clinical samples, AFIAS sensitivity and specificity were 99.8% and 99.3% for the HBsAg test, 100.0% and 100.0% for the anti-HBs test, and 98.8% and 99.1% for the anti-HCV test, respectively. Its agreement rates with the Elecsys HBsAg, anti-HBs, and anti-HCV detection assays were 99.4%, 100.0%, and 99.0%, respectively. AFIAS detected all samples with HBsAg genotypes A-F and H and anti-HCV genotypes 1, 1a, 1b, 2a, 2b, 4, and 6. Cross-reactivity with other infections was not observed. Conclusions: The AFIAS HBsAg, anti-HBs, and anti-HCV tests demonstrated diagnostic performance equivalent to current automated CLIAs. AFIAS could be used for a large-scale HBV or HCV screening in low-resource laboratories or low-to middle-income areas.

• Korean Chemical Engineering Research
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• v.57 no.3
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• pp.305-312
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• 2019

The discovery of nitric oxide (NO) as a major signaling molecule in a number of pathophysiological processes - vasodilation, immune response, platelet aggregation, wound repair, and cancer biology - has led to the development of various exogeneous NO delivery systems. However, the development of ideal delivery system for human body application is still left as a challenge due to its high reactivity and short half-life in physiological condition. In this article, an overview of several nano-structures as potential NO delivery system will be presented, along with their recent research results and biomedical applications. Nano-size delivery system has immense advantages compared to others due to its high surface-to-volume ratio and capability for surface modification; thus, it has been proven to be effective in delivering nitric oxide with enhanced performance. Through this novel nano-structure delivery system, we are expecting to achieve sustained release of nitric oxide within adequate range of concentration, which ensures desired drug effects at the target site. Among different nano-structures, in particular, nanoparticle, microemulsion and nanofilm will be reviewed and compared to each other in respect of nitric oxide release profile. The proposed nano-structures for exogeneous NO delivery have a biological significance in that it can be further utilized in diverse biomedical fields as a highly promising therapeutic method.

• Clean Technology
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• v.29 no.2
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• pp.118-125
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• 2023

Once a site is contaminated with polychlorinated biphenyls (PCBs), serious environmental and human health risks are inevitable. Therefore, innovative but economical in situ remediation technologies must be immediately applied to the contaminated site. Recently, nanoscale zero-valent iron (nano-ZVI) particles have successfully been applied for the dechlorination of various chlorinated organic compounds like TCE, PCE and DDT, and they are considered to be environmentally safe due to the high abundance of iron in the earth's crust. Nano-ZVIs are much more reactive than granular ones, but tend to agglomerate due to their high surface energy and magnetic properties. In order to prevent them from being agglomerated toward larger particles, TiO₂ was used as a support to immobilize the nano-ZVI particles as much as possible. 10wt% ZVI/TiO₂ was prepared by adding NaBH₄ slowly into an FeSO₄/TiO₂ aqueous slurry. In spite of their non-uniformity in size, the nano-ZVI particles were quite successfully dispersed onto the exterior surface of a non-porous TiO₂ powder. The ZVI/TiO₂ was then employed to degrade Aroclor 1242, a kind of PCBs standard, in spiked soil, and its reactivity towards the degradation of Aroclor 1242 was investigated. The fabricated ZVI/TiO₂ degraded Aroclor 1242 in soil quite effectively, but the creation of remaining dechlorinated compounds, possibly high molecular weight hydrocarbons, in the soil was unavoidable.