• Mycobiology
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• v.40 no.1
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• pp.27-34
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• 2012

Fifty three fungi isolated from soils of different microhabitats of eastern Himalayan range (3,400-3,600 msl) were screened for mycosynthesis of silver nanaoparticles (AgNPs) and their efficacy as antimicrobials were assessed in combination with commonly used antibiotics. Three isolates $Aspergillus$ $terreus$ SP5, $Paecilomyces$ $lilacinus$ SF1 and $Fusarium$ sp. MP5 identified based on morphological and 18S rRNA gene sequences were found to synthesize AgNPs. These nanoparticles were characterized by visual observation followed by UV-visible spectrophotometric analysis. The AgNPs synthesized by $Aspergillus$ $terreus$ SP5, $Paecilomyces$ $lilacinus$ SF1 and $Fusarium$ sp. MP5 showed absorbance maxima at 412, 419, and 421 nm respectively in the visible region. Transmission electron microscopy micrograph showed formation of spherical AgNPs of 5-50 nm size. The antimicrobial activity of the mycosynthesized nanoparticles were investigated alone and in combination with commonly used antibiotics for analysis of growth inhibition zone against test organisms, namely, $Staphylococcus$ $aureus$ MTCC96, $Streptococcus$ $pyogenes$ MTCC1925, $Salmonella$ $enterica$ MTCC735 and $Enterococcus$ $faecalis$ MTCC2729. The mycosynthesized nanoparticles showed potent antibacterial activity and interestingly their syngergistic effect with erythromycin, methicillin, chloramphenicol and ciprofloxacin was significantly higher as compared to inhibitions by AgNPs alone. The present study indicates that silver nanoparticles synthesized using soil borne indigenous fungus of high altitudes show considerable antimicrobial activity, deserving further investigation for potential applications.

• Korean Journal of Materials Research
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• v.32 no.2
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• pp.94-97
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• 2022

We fabricated 3 types of ETL, mp TiO₂, ZnO, and ZnO coated on mp TiO₂(ZMT) to compare the photoelectric conversion efficiency (PCE) and fill factor (FF) of Perovskite solar cells. The structure of the cells was FTO/ETL/Perovskite (CH₃NH₃PbI₃)/spiro-MeOTAD/Ag. SEM morphology assessment of the ETLs showed that mp TiO₂ was porous, ZnO was flat, and the ZMT porous surface was filled with a thin layer. Via XRD measurements, the crystal structures of mp TiO₂ and ZnO ETL were found to be anatase and wurtzite, respectively. The XPS patterns showing energy bonding of mp TiO₂, ZnO, and ZMT O 1s confirmed these materials to be metal oxides such as ETL. The electrical characteristics of the Perovskite solar cells were measured using a solar simulator. Perovskite solar cells with ZMT ETL showed showed PCE of 10.29 % than that of conventional mp TiO₂ ETL devices. This was considered a result of preventing Perovskite from seeping into the ETL and preventing recombination of electrons and holes.

• Journal of Powder Materials
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• v.25 no.3
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• pp.232-239
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• 2018

In this paper, the recovery and nanoparticle synthesis of Ag from low temperature co-fired ceramic (LTCC) by-products are studied. The effect of reaction behavior on Ag leaching conditions from the LTCC by-products is confirmed. The optimum leaching conditions are determined to be: 5 M $HNO_3$, a reaction temperature of $75^{\circ}C$, and a pulp density of 50 g/L at 60 min. For the selective recovery of Ag, the [Cl]/[Ag] equivalence ratio experiment is performed using added HCl; most of the Ag (more than 99%) is recovered. The XRD and MP-AES results confirm that the powder is AgCl and that impurities are at less than 1%. Ag nanoparticles are synthesized using a chemical reduction process for recycling, $NaBH_4$ and PVP are used as reducing agents and dispersion stabilizers. UV-vis and FE-SEM results show that AgCl powder is precipitated and that Ag nanoparticles are synthesized. Ag nanoparticles of 100% Ag are obtained under the chemical reaction conditions.

• Analytical Science and Technology
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• v.17 no.5
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• pp.438-442
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• 2004

To determine the contents of $^{99}Tc$ in the spent PWR (pressurized water reactor) nuclear fuels by ICP-MS (inductively coupled plasma-mass spectrometry), a technetium separation method using an extraction chromatographic resin (TEVA Spec resin) has been established. $^{99}Tc$ was separated from a spent PWR nuclear fuel solution by this separation procedure and its concentration was determined by ICP-MS. The result agrees well with the value calculated by the program ORIGEN 2 and also the value measured by AG MP-1 resin/ICP-MS method described in our previous paper. It can be concluded that the present separation procedure is superior to the AG MP-1 resin procedure with respect to the time required for technetium separation as well as the efficiency of decontamination from other radioactive nuclides.

• Proceedings of the International Microelectronics And Packaging Society Conference
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• 2003.11a
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• pp.80-83
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• 2003

본 연구에서는 고온 솔더 범프와 저온 솔더 패드를 이용하여 $140^{\circ}C$에서 1분간의 리플로 공정을 통해 접합에 성공하였다. 고온 솔더 범프로 Sn-4.0Ag-0.5Cu 솔더 볼을 사용하였고, 저온 솔더는 In-48Sn $(mp:\;117^{\circ}C)$ 솔더를 기판에 evaporation 방법으로 두께 $20\;{\mu}m$의 패드 형태로 증착하였다. $140^{\circ}C$에서 1분간의 리플로 공정을 통해 칩과 기판을 접합하였으며, 접합 단면을 관찰해 본 결과 저온 솔더가 녹아 고온 솔더에 wetting된 것을 관찰하였다. 이 시편을 상온에서 시효처리를 실시한 결과 시간의 경과에 따라 저온 솔더와 고온 솔더가 상호 확산하여 약 $40\;{\mu}m$였던 확산층의 범위가 점차 증가하는 것을 관찰할 수 있었다. 또한, 리플로 공정변수에 따른 솔더의 미세구조 변화 및 ball shear strength등의 기계적 특성에 대해 고찰하였다.

• Bulletin of the Korean Chemical Society
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• v.29 no.1
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• pp.69-75
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• 2008

Tautomerism of pyrimidine base cytosine has been comparatively examined on nanoparticle and roughened plate surfaces of silver, gold, and copper by surface-enhanced Raman scattering (SERS). The SERS spectrum was found to be different depending on the metals and their substrate conditions suggesting the dissimilar population of various tautomers of cytosine on the surfaces. The ab initio calculations were performed at the levels of B3LYP, HF, and MP2 levels of theory with the LanL2DZ basis set to estimate the energetic stability of the tautomers with the metal complexes as well as the gas phase state. The amino group and N3-coordinated tautomer was predicted to be more favorable for bonding to Au, whereas the hydroxyl and N1-coordinated zwitter ionic form is most stable with Ag and Cu as a bidentate form from the DFT calculation. The binding energy with the Ag atom is calculated to be smaller than those with the Au and Cu atoms in line with the temperature-dependent SERS spectra of cytosine.

• Bulletin of the Korean Chemical Society
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• v.24 no.11
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• pp.1686-1688
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• 2003

• Journal of the Korean Chemical Society
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• v.44 no.6
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• pp.581-586
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• 2000

Separation and coulometric titration method were applied for the determination of plutonium content in samples of PWR spent fuel. Plutonium was separated on an anion exchange(AG MP-1) column and determined by the controlled-potential coulometric titration. In this study, we discussed some experimental conditions related to the separation and determination of plutonium in PWR spent fuel samples. Average accuracy(recovery of plutonium) for the determination of 0.230∼3.02 mg plutonium standard was 99.36%. Average precision(relative standard deviation, RSD) for the determination of 0.250∼0.450 mg plutonium in PWR spent fuel samples was 0.38%.

• Journal of the Mineralogical Society of Korea
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• v.29 no.4
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• pp.221-227
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• 2016

Copper is an essential transition metal involving in various biogeochemical processes. With the recent advances in analytical techniques and mass spectrometry, such as MC-ICP-MS, it is possible to measure Cu isotopes, which allows us to understand various biogeochemical processes in detail. Nonetheless, few studies have been performed in South Korea. In this study, we compared two purification methods previously reported using an anion exchange resin ($AG^{(R)}$ MP-1M), developed the best method in our lab environment, and then verified it by measuring Cu isotopic compositions in two USGS geological reference materials (BHVO-2 and BIR-1a). Although all matrix cations causing mass bias were effectively removed through both two methods with the yield of better than 95%, the method using the mixture of HCl and $H_2O_2$ only displays Cu isotopic compositions, in excellent agreement with reported values within the error. The method developed in this study is expected to be commonly applied to earth and environmental sciences.

• Asian Pacific Journal of Cancer Prevention
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• v.17 no.3
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• pp.1009-1014
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• 2016

It is not clear how gene polymorphisms affecting drugs can contributes totheir efficacy in multiple myeloma (MM). We here aimed to explore associations among gene polymorphisms of tumor necrosis factor alpha (TNFalpha), nitric oxide synthesis 3 (NOS3) and multi-drug resistance 1 (MDR1), clinical parameters, prognosis and survival in MM patients treated with VAD (vincristine-adriamycine-dexamethasone), MP (mephalane-prednisolone), autolougus stem cell transplantation (ASCT), BODEC (bortezomib-dexamethasone-cyclophosphamide) and TD (thalidomide-dexamethasone). We analyzed TNFalpha, NOS 3 and MDR1 in 77 patients with MM and 77 healthy controls. The genotyping was performed with PCR and/or PCR-RFLP. There was no clinically significant difference between MM and control groups when TNFalpha (-238) and (-857) and MDR1 gene polymorphisms were studied. However, the TNFalpha gene polymorphism (-308) GG genotype (p=0.012) and NOS3 (+894) TT genotype (p=0.008) were more common in the MM group compared to healthy controls. NOS3 (VNTR) AA (p=0.007) and NOS3 (+894) GG genotypes (p=0.004) were decreased in the MM group in contrast. In conclusion, the NOS3 (+894) TT and TNFalpha (-308) GG genotypes may have roles in myeloma pathogenesis.